My biggest concern is the keyboard. I have a "touch" and I find the learning curve on typing is quite steep.
I've had either a Palm/Treo or a Blackberry for years now (gone back and forth) and have gotten very fast with the real keyboard. But the screen is giving me fits. I'm sure I'll get better, but that's my biggest complaint.
Aside from that, the "touch" is the Palm Pilot I always wanted and they could never seem to make. I really think the Touch/iPhone is the greatest software/hardware project to ever hit the retail scene. Prior to the touch, I used to say the same about the Harmony Universal Remote ... but the touch wins. (If you don't know about Harmony Remotes ... check 'em out!)
I'd like to go iPhone - but for me to do it would require a GSM repeater in my apartment ... our building is really old and thick and only Verizon penetrates all the way into my place. I think I can get a repeater for about $250 ... may do it ...
My dad is making displays for small devices and may revolutionize the space if his company succeeds ... they make a display that uses 1/4 the power for the same brightness and a wider color gamut compared to current devices. You'll get hours and hours of brilliant video off one battery charge ...