No matter the operating system, the One M8 is still a gorgeous phone. The brushed aluminum rear panel, painted a sleek gunmetal gray, wraps around the phone like a warm embrace. There's not one, but two cameras situated along the top of the rear panel, flanked by an LED flash.HTC etched the Verizon and 4G LTE emblems into the phone's rear panel, which looks sleek and classy. Like its Android brethren, the M8's 5-inch display sits between two gray plastic panels housing the BoomSound speakers. The company ditched the physical buttons from the M7 in favor of touch-screen icons, leaving a gleaming chrome HTC emblem in their place.

A glossy, black IR blaster occupies the majority of the top of the phone, with the power button integrated into the right corner. The microSD card is located directly above the volume rocker, while the micro SIM slot is found on the left. Both the micro USB and the headphone jack sit at the bottom of the device.

Just like the Android version, the Windows Phone M8 measures 5.8 x 2.8 x 0.37 inches and weighs 5.64 ounces. It's heavier than the Samsung Galaxy S5 (5.1 ounces, 5.6 x 2.9 x 0.3 inches) and the Apple iPhone 5s (3.95 ounces, 4.87 x 2.31 x 0.30 inches).

The display is just as gorgeous on the Windows edition of the One M8 as it is on Android. Live Tiles were a symphony of vivid color on the 5-inch 1920 x 1080-pixel panel. Chadwick Boseman's mahogany skin tone in the 1080p Get On Up trailer looked warm and inviting against his royal-blue sateen suit. Details were sharp enough to make out some of the inscription on his huge gold ring and the folds and creases in the suit.

When we measured the phone's color reproduction capabilities, the Windows Phone displayed 114 percent of the sRGB gamut, which is just a hair behind the Android model (115 percent), but enough to beat the iPhone 5s' 98 percent. The Samsung GS5 owned the competition, at 156 percent.

As far as color accuracy, the Windows One M8 didn't perform as well as I expected on the Delta-E test, scoring 5.1 (0 is best). It beat the GS5's 5.9, but the Android One M8 and the iPhone had much better results of 4.1 and 0.09.

Still, the Windows One M8 outshone most of the competition, measuring 420 nits on our light meter -- much brighter than the 350-nit smartphone average, the Android version (368 nits) and the Galaxy S5 (347 nits). However, the iPhone delivered an even-brighter 470 nits.

Like the Android model, HTC's impressive front-facing BoomSound speakers effortlessly filled my small test space with loud, clear audio. When I listened to it in my empty office, the audio quality was on a par with some of the lower-end Bluetooth speakers on the market.

There was no lack of bass when I listened to Nicki Minaj's "Anaconda." The speakers faithfully reproduced the artist's frenetic delivery as she switched between high-pitched staccato and drawn-out drawl.

However, I noticed that the accompanying horns on the track sounded scratchy at max volume, signaling that the speakers can't handle highs as well as mids and lows. The problem persisted when I switched to Anita Baker's rendition of "Lately." While Baker's scintillating alto was rich and full, there were some points throughout the song where I found myself distracted by overly brassy cymbals and strings.

The Windows One M8 measured 88 decibels on the Laptop Mag Audio Test, topping the 80 dB smartphone average. The Android edition hit 83 dB, while the GS5 notched 73 dB.

A gorgeous phone with a good-looking operating system -- what could possibly go wrong? Thankfully, not much. As the name suggests, this version of the HTC One M8 runs Windows 8.1, which adds some of the features Android and iPhone owners have been enjoying for some time.

For example, a swipe down reveals the notifications shade that the folks over at Microsoft have helpfully renamed the Action Center. From there, you can check out your latest updates and access the quick settings menu. It allows only four settings at a time, but you can swap them out in the full settings menu. It's nice, but I wish I could access more than four at a time.

A long press of the back button shows all your currently opened apps. Instead of making you repeatedly hit the back button to exit everything, you can now hit the X in the corner of the app to close out a program.

My favorite Windows Phone 8.1 feature is the ability to dismiss the capacitive home, back and search at the bottom of the screen. A small arrow button in the far left corner will hide the black bar beneath the display, restoring about a quarter inch of the display. If you swipe up from the bottom of the display, the bar will resurface.

With Windows Phone 8.1, Microsoft has finally added trace-typing technology to its virtual keyboard. When I traced my finger along the slim, gray keys, it produced a thick blue line that kept pace with my frantic swivels. The color of the line changes according to the Live Tile palette theme selected in the Settings menu.

Psst, don't tell Master Chief, but somebody put Cortana in my phone! Hoping to draw in fans of the Halo series, Microsoft has created a digital assistant voiced by the beloved smart artificial intelligence construct Cortana.

Like Siri and digital assistants such as Samsung's S Voice and Google Now, Cortana is there to help schedule meetings, look up restaurants and answer a few questions along the way. Microsoft made sure to infuse Cortana with a sense of humor. When I asked if she would be appearing in Halo 5, she responded sounding somewhat amused, "Of all the questions you could have asked."

When I wasn't asking about Master Chief or the Covenant, Cortana handled regular inquiries fairly quickly, informing me about the next day's weather, when the new season of "Scandal" is scheduled to start and what's going on in Ferguson, Missouri. Some questions, such as those about the weather, got a voice response, while others, like "Scandal" one, just pulled up Web results.

One of the signature features of HTC's smartphones is BlinkFeed, a Flipboard-esque interface that pulls in content from news sources and your social networks. I was glad to see that it made its way to the HTC One 8 for Windows, but it's missing a few features found on the Android version.

For starters, you can't swipe right from the home screen to launch BlinkFeed. Instead, it's presented as a Live Tile. It's a minor annoyance, but an annoyance nonetheless. I was disappointed to discover that the restaurant-suggestion feature was absent. Also missing is the Fitbit integration that HTC has been promising to roll out. To be fair, it's not yet on the Android HTC One M8, either.

Similar to the Motorola Moto X and LG's KnockON feature, Motion Launch lets you double tap the HTC One's display to wake up the phone. But other features found on the Android version, such as swiping up to launch a recently used app or swiping down to place a voice call, are noticeably missing.

In order to take advantage of that large IR blaster at the top of the phone, HTC has added the HTC Sense TV app. Sense TV allows you to control your television, cable box and home theater using the One M8. Once you get the app set up, you can change channels and output settings, as well as adjust the volume, without having to hunt down a dozen remote controls.

It took me about 5 minutes to pair my ViewSonic TV and Scientific Atlanta Explorer cable box to the remote. Once it was set up, I went into full couch-potato mode, channel surfing at my leisure. HTC also added a streaming feature so I could switch over to my Hulu Plus account if I couldn't find anything on the regular boob tube.

Despite all the new OS additions, Microsoft remains at a disadvantage compared to Android and iOS, thanks to its relatively small app store. The Windows Phone store recently passed the 300,000-app mark, but it's a drop in the bucket compared to the 1 million-plus apps featured in the Google Play and the Apple App stores.

Microsoft has been working to bring some of the more popular apps on Android and iOS over to Windows. Instagram has finally arrived on Windows, but it's still in beta. You'll also find Vine, Spotify, Netflix, LinkedIn, Uber and Hulu Plus. However, Snapchat, YouTube, Google Maps and Secret are still MIA.

HTC employed a rather light touch when it came to preinstalled apps on the Android version of the One M8. Other than Sense TV and BlinkFeed and several camera apps, HTC-branded apps on the Windows One M8 are few and far between.

Verizon added several of its mainstay apps, including NFL Mobile, VZ Navigator, Verizon Messages and MyVerizonMobile.

Facebook and Slacker Radio are the only two third-party apps preloaded onto the device.

Using Qualcomm's powerful 2.3-GHz quad-core Snapdragon 801 CPU with 2GB of RAM, the HTC One M8 for Windows can stand toe-to-toe with just about any rival flagship phones currently on the market. The phone also has 32GB of onboard storage, and accepts microSD cards up to 64GB.

I unleashed my inner speed demon on Asphalt 8: Airborne, tearing past other drivers and drifting through turns. Graphics were gorgeous on the One M8 and showed no signs of slowing down or jaggies, even as I engaged maximum nitrous to secure the lead. Navigating and opening apps were both swift experiences, and it took just half a second to launch the camera.

The One M8 scored 535.59 on the WP Bench test, which measures CPU, memory, storage and GPU performance. The Nokia Lumia Icon and its 2.2-GHz Qualcomm Snapdragon 800 CPU notched 464.18.

On the SunSpider JavaScript test, the One M8 hit 527.9 milliseconds, which is noticeably faster than the Icon, which finished in 542.9 ms.

When I ran the Peacekeeper Browser test, the One M8 scored 508, which is better than the Nokia Lumia Icon's 322, but falls slightly behind the Icon's 520.

You want fast? Verizon's got fast. The HTC One M8 for Windows delivered blistering Web speeds over Verizon's 4G LTE AWS network. I saw an average download speed of 57.8 Mbps at the Laptop Mag office in the Flatiron District of New York City. Upload speeds were equally impressive, at 14.16 Mbps.

While it's not the first smartphone to sport two rear-facing cameras, the HTC One M8 might make the best use of them. Not only can the Duo Camera capture 3D-like images, but it also lets you alter the focus of your photo after you've taken it.

The larger of the two cameras employs a 4-MP Ultrapixel sensor, which serves as the primary shooter. The One M8 snaps a beautiful picture. When I took a test shot of some sunflowers at my favorite bodega, the camera delivered bright, golden petals with a warm, chocolate-colored core. The pink carnations at the bottom of the shot were vibrant and rich, even if they were out of focus. Details were sharp enough to see the delicate fuzz on the back of the light-green petals.

The One M8's camera takes quality low-light photos both with and without the flash. Despite the dim setting, the camera accurately captured my test subject's skin tone and some of the tiny polka dots on his shirt.

The One M8 captures video just as well as it takes stills. In my 1080p test video on a busy New York City street, taxis whizzed past in a pleasant shade of gold. I easily read the text on the H&M awning across the street, as well as the ads on top of the cabs and the side of a bus. However, I wish HTC had added an optical image stabilization feature, as I found videos were relatively jumpy.

Selfie fanatics will appreciate the 5-megapixel front-facing camera. A test image of Anna, Laptop Mag's Managing Editor, yielded fairly accurate colors, such as my olive-and-black dress and her blond locks. While there was some fuzziness in the 2460 x 1440p image, I could still make out the individual strands of Anna's hair.

It just kept going and going and going ... The HTC One M8 for Windows lasted 10 hours and 28 minutes on the Laptop Mag Battery Test (continuous Web surfing over Verizon's 4G LTE network at 150 nits). That's more than 2 hours longer than the 8:07 smartphone average.

The Android version of the One M8 isn't a slouch, clocking in at 9:52, while the Samsung Galaxy S5 tapped out at 9:42. The Apple iPhone 5s went down for the count after 5:46.