one of the most important parts of the UI, the "cards," but not much else. The black space is dotted with soft LED lights that glow when you swipe your finger across it -- a nice touch.
The screen itself is a sensitive capacitive touchscreen, which seems as responsive (if not more) than the iPhone's display. The resolution is the same as Apple's device (480 x 320), though due to its smaller size, it has slightly higher pixel density. Colors looked bright and clear, and overall the screen was sharp and easy to read. The high gloss may cause issues in the sun, but most modern touchscreen phones seem to deal with the problem, and we expect no less from this one.
The UI itself is absurdly slick -- certainly on par with the iPhone's interface and HTC's TouchFlo 3D. There are smooth zooms, transitions, and fades in and out of content, and there's little noticeable lag or stutter when moving through actions. Fonts are tastefully chosen, and the icons are akin to OS X's or Vista, with soft shadows underneath and lots of dimension.
Using the interface is mainly accomplished with swipes along the screen and by pushing the center button. A quick swipe up with your thumb slides a launcher (essentially a prettied up traditional Palm app screen) over your current state. What's notable is that you never leave the application you're in to do this. It goes up, then it goes away. Unlike the iPhone (which is really its nearest competitor), webOS provides true multitasking, allowing you to switch between active apps. You don't have to close and reopen, just shuffle through your programs. If you switch to another app, the UI scales back the program you're in down to that deck of "cards," then zooms up the new selection. By pressing the center button on the phone, you zoom out all of your cards, and can swipe through them to find what you're looking for. The content inside of the cards isn't just a snapshot like tabs in Mobile Safari -- they're live applications that can be flipped and manipulated. You can also rearrange the cards in any order by touching and holding, then sliding them around. Gestures can also be used to move back and forward in a document or webpage (swipe left or right), and there's a gesture used to bring up a quick launcher "wave" over top of whatever application you're in.