That being said, I can't help but feel that HTC's UI is starting to seem just a teensy bit stale compared to the fresh and modern design introduced in Google's base Lollipop OS. It's the old case of change for the sake of change -- and as the base Android OS gets more and more visually compelling, it gets increasingly difficult to justify the benefit of sticking with an arbitrarily different alternative.
HTC does, at least, offer options in some areas. For instance, while the grid-based design of HTC's app-switching interface feels dated and clunky next to Lollipop's more elegant card-based layout -- and is oddly glitchy, too, with apps sometimes flickering briefly when you switch between them -- HTC provides the ability to ditch its approach and go with Google's instead.
Similarly, HTC's app drawer defaults to sorting apps in a somewhat random order, with lots of icons hidden in folders that aren't always obvious. You can switch to a more logical alphabetical approach, which makes things immensely easier to find, but only if you go out of your way to track down and toggle that setting. It's nice that such choices exist, but you shouldn't have to work to get a good user experience; excellence should be the standard everyone sees out of the box.
Still, the M9's software is generally tasteful and cohesive. And basic UI aside, HTC has added in some nice features, like a new advanced theming center that makes it fun and easy to tweak the look of your phone's environment. You can browse through dozens of options for changing things like icons, fonts and the style of system-level elements. You can even have the phone create a theme on demand to match any photo or image you want as your wallpaper, with complementary colors and icons throughout the system.
The M9 also allows you to change the order of the main Android navigation buttons, if you get the urge. You can even add a fourth button into the mix, though the usefulness of that is debatable. (The options for an additional button include shortcuts for turning off the screen, opening the notification panel, hiding the navigation bar, opening the Quick Settings panel and toggling the phone's auto-rotate feature.)
More useful is the ability to customize what functions appear in the One's Quick Settings panel. That capability allows you to fill the menu with things you actually need and eliminate those you don't frequently use.
BlinkFeed -- HTC's Flipboard-like news-reading panel that lives at the left side of the home screen -- is also back on the M9. I find I rather enjoy flipping over to it and scrolling through stories when I have a few minutes to kill, but you can always remove it if you don't agree. The same goes for HTC's new home screen widget, which attempts (with varying degrees of success) to predict what apps you might want to use based on whether you're at home, at work or out and about (and also offers some questionable suggestions for new app downloads).
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