Drawbacks: you can't enter calendar events; you have to download them from your computer. Also, it won't play any RealAudio files. Ubu.com files are too big to play, and there's no cut and paste. Other than that, it's mind-gobblingly brilliant. I could play live shows with this, and it does the web wherever there's wifi -- kind of dangerous for me; I'll never be offline.
Also saw the new New Museum (the SANAA-designed one, due to open on December 1st) on the Bowery today. Will post a photo from the laptop; it's theoretically possible to do from an iPod Touch, but clunkissimo.