The new curvy design language doesn't feel like a strict departure from the G1, despite the many differences, instead the phone seems like a continuation of the "friendly" design nature of HTC's Android phones. We like it plenty, with a shiny look that doesn't make the phone look or feel too "plastic."
The rollerball is hardly a departure from the G1, and in fact, none of the internals are different either. HTC has tweaked the camera slightly, so it should be more responsive -- along with the video recording functionality courtesy of Cupcake. That also means that the pesky ExtUSB jack has popped up again, since this phone has been in the pipeline since before HTC discovered that 3.5mm jacks are a Pretty Good Idea -- though we get the impression they've learned their lesson, and won't be bothering us with these adapters for too much longer.
Cupcake is a good update, but might need some improvement, since we managed to crash the software keyboard without too much trouble. The keyboard's methods of notification for key-presses includes sound, vibration and these odd "fireworks" letters that pop up in seemingly random locations instead of directly above the keypress. The portrait keyboard is certainly cramped, but the inclusion of proximity correction and the word guessing games and auto-correction Android includes should ease the pain.
Cupcake also brings built-in video recording and playback. We tested it and it works fine, but playback of recorded video is not exactly awe-inspiring in the frame rate or quality department -- perhaps there was a reason Google didn't put video recording into the first generation. Still, it's video, and it works.
We weren't able to check out Cupcake's new Gmail app on the phone, since the phone hadn't been set up for a Google account, but we hear good things, including checkboxes in the list view for mass archive and delete functions.