HTC's stunning sequel steals the show

The Good The HTC One M8's sumptuous aluminum body makes a beautiful background for this top-flight smartphone's brilliant 5-inch display. It runs on a powerful quad-core processor and Android KitKat, the stereo speakers deliver excellent sound, and the depth-sensing camera brings a ton of useful features.

The Bad The One M8’s battery is not user-removable, making it harder to replace once the battery inevitably wears out. The phone's sealed chassis is not water-resistant, and the One M8's photos look less sharp than competitors'.

The Bottom Line Elegant style, raw power, and sophisticated features make the HTC One M8 an excellent smartphone choice for anyone but the most exacting photographer.

Think of the HTC One M8 as the big-budget sequel to an Oscar-winning indie film. Last year's HTC One won rave reviews and obsessed fans, but not enough customers to keep HTC growing. This year, HTC needs a rip-roaring box-office hit with its flagship phone.

It could happen. The One M8 is undeniably the most impressive handset the company has ever minted. Like its predecessor, the M8 brings a refined and beautiful software and speedy performance, all wrapped in a lithe and eye-catching aluminum skin.

The HTC One M8 must compete head-to-head against its archrival's freshest mobile machine, the Samsung Galaxy S5, and compete it does. Aesthetically speaking, the HTC One M8 runs rings around the GS5 with its elegant and intuitive Sense interface. What's more, though the M8 may lack every bell and whistle that Samsung packs into its phones, it matches the GS5 on almost every feature that really matters, from processing speed to user interface. Only the camera and its ever-so-slightly muddy shots give me pause.

Design

When the original HTC One hit the mobile scene last year, I was stunned by its sophisticated all-metal unibody chassis. Not only was it sturdy and comfortable to grip, but thanks to a smoothly curved back and matte finish, its polished edges elevated the handset to an unprecedented level of luxury. Frankly I'd never seen a handset look that good, and I've handled a lot of mobile phones.

Designwise, this certainly sets the bar high for any subsequent smartphone, let alone an HTC One follow-up. I can confirm, though, that the new HTC One M8 is one heck of a handsome device -- the sexiest smartphone I've seen all year, in fact (including the Galaxy S5 and the Sony Xperia Z2). While HTC's latest creation is more conservatively styled than the previous One, it has a look that's just as premium.

For instance the M8's bezel (where the screen and phone edge meet) is alluringly reflective and convincingly conveys that you're holding a luxury handset. Even so, the bezel is not polished to the same eye-catching sheen as the first One was. I also found the back surface of my M8 review device, though lovingly minted in a classy brushed-metal motif, smoother than the old HTC One, which had a roughness almost like a ceramic bowl. Indeed this gray M8's slicker texture doesn't wick away moisture quite as effectively. The result is a slippery, more friendly canvas for grease than its predecessor's matte back.

To be clear, the One M8 comes in two additional colors (silver and gold) that don't sport the brushed-metal pattern (which HTC calls "hairline"). The fallout is that both the silver and gold versions of the M8 lack the gray model's slippery feel. And in other ways the M8 is just as beautiful as its predecessor. It uses a gorgeous all-aluminum body that flaunts a similar curved backing. The M8 also feels superbly solid, strong, and well-constructed.

I admit these are minor issues and nitpicking on my part since the M8 brings important design improvements to the HTC One franchise. Notably the phone's screen is now larger -- 5 inches across (as opposed to the HTC One's 4.7-inch screen). And unlike the first One, HTC says the One M8's chassis is truly built entirely from metal. By contrast the company explained the original One's body was 70 percent aluminum, the rest being plastic.

Additionally the M8 sports a pair of powerful stereo speakers that flank the display. Also branded by HTC as BoomSound, these front-firing grilles belt out a ton of sound, at least for a mobile phone. Even better, the M8 is definitely louder and produces sound with way more presence than last year's model. It's to be expected, since HTC says it enhanced the M8's BoomSound audio system by cranking up the volume by 25 percent and improved its frequency range. Don't just take my word for it. Be sure to check out our deep dive into the HTC One M8's upgraded audio prowess.

Despite the phone's larger display, the device remains roughly the same size, thickness, and weight. Tipping the scales at 5.4 ounces (154.2 grams), the M8 understandably stands a little taller yet is just slightly heavier than the older One (5.04 ounces/142.9 grams). It's heavier than the Galaxy S5, too (5.1 ounces/145 grams) even though the M8 lacks extra hardware such as a heart-rate monitor and fingerprint scanner.

Display

From the moment I picked up the HTC One M8, I knew its big 5-inch screen was high-quality. While it can't produce the same deep blacks and vibrant colors conjured by the OLED displays you'll find in Samsung Galaxy handsets such as the Note 3 and GS4, the M8's IPS LCD has a lot going for it. Specifically these are admirably wide viewing angles, a pleasing amount of brightness, plus rich colors.

With a full HD resolution (1,920x1,080 pixels), photos, video, and text were also crisp on the phone's screen even if it has a marginally lower pixel density than the original One (which had the same number of pixels on a smaller 4.7-inch screen). All this adds up to a display that does justice to any visual content you choose to enjoy on the M8.

Some words of warning though; if you choose to view the One M8's screen in the great outdoors, I suggest you do so without polarized sunglasses. When I did this with my pair of Ray-Bans, the phone's screen in portrait orientation was dim to the point of being unreadable. Flipping the One M8 into landscape position wasn't a problem and the display was just as bright as usual under these conditions.

Software and interface

Premium design isn't the only ace in the One M8's hand. The handset runs Google'sAndroid 4.4.2 operating system, the latest iteration from the tech giant. KitKat brings a cleaner, less cluttered layout, tighter integration with Google search, plus faster performance (especially on devices with lower specs). Layered on top of that is HTC's most recent revamp of its Sense UI, version 6 (see next section). As you'd expect from a smartphone churning such modern mobile software, the M8 has access to all of Google's bells and whistles.

This includes Gmail, Google plus social networking, the Chrome browser, and Drive file storage. The phone also taps into the company's vast universe of media content via Google's Play digital storefront. That means that books, movie rentals and purchases, games, and the more than 1 million apps hawked by third-party developers are just a finger tap away.

You'll find the futuristic Google Now personal notification system onboard, too, either in widget form or launched by swiping upward from the bottom of the screen. It provides insightful reminders, suggestions, and directions automatically based on your past search history, time, and location data. It's the driving force behind the Google Wear operating system for smartwatches, clothing, and other wearable tech gear.