The HTC One runs custom HTC software based on Google's Android 4.1.2 (Jelly Bean) operating system. (I asked HTC if and when the phone would be upgraded to the more current Android 4.2 release, but representatives were unable to provide a specific answer.)
BlinkFeed is a Flipboard-like news stream integrated directly into the launcher.
The One's user interface is quite different from what you'll see on other Android devices, including past HTC phones. First and foremost, the default home screen panel is taken up by something called BlinkFeed -- a Flipboard-like news stream integrated directly into the launcher. You can set it up to include content from a limited range of specific websites or opt to add broad categories like business, entertainment and gadgets -- along with content from a few different social networks -- into your stream.
I found the BlinkFeed concept to be sensible enough in theory; many novice users won't search for apps and configure their home screens on their own, and BlinkFeed provides a nice starting point for easing such people into the smartphone world. It's well-designed, too, and easy to use (though I did find I received fresher, more diverse and more frequently updated content from Flipboard).
That said, a lot of users aren't going to want BlinkFeed as a permanent part of their lives -- and HTC doesn't provide a way for you to remove it entirely from the phone. I'm not sure why HTC didn't create it as a removable widget instead of baking it into the launcher; that would have allowed much more flexibility while still achieving the same effect.
You can, at least, deactivate BlinkFeed and ignore it if you want. When you swipe over to the right of BlinkFeed, in fact, you'll find a more traditional home screen setup. You can add up to three more traditional panels and set any of them to be the default. (BlinkFeed will always remain on the left-most panel.)
BlinkFeed aside, HTC's new user interface is flatter and more visually subdued than those the company has created in the past. Still, many of the UI changes feel rather arbitrary and unnecessary -- change for the sake of change -- and some of them actually make the user experience less intuitive than what Google's stock Android software would have provided.
Widgets exist in a separate area that's accessible via the phone's main settings menu.
To add a shortcut from the app drawer to your home screen, for instance, you can't just hold it and drag it into place; instead, you have to press and hold the icon, look for a "Shortcut" icon that appears at the top of the screen, drag the app to that icon, and then go about placing it on your home screen.
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