I love everything about it compared to my Treo 300, which I also loved; the smaller size, the brighter screen, the lack of a flip cover, the navigation buttons, the improved GUI which no longer requires a stylus for most things, the sold feel, the rounded shape, the better sound, the faster processor, I could go on and on (and I probably will, sorry).
But the thing I really love is having a built in camera. Happy snaps! You have been warned. I carry my 'phone everywhere, and consequently I now carry my camera everywhere. Even on my bike...
Scenes from my ride yesterday:
Yeah, it isn't professional quality, but hey, it works. I love it!