I agree with jeep99; no 3G (let alone 3.5G) is a big drawback when using the device to access the internet on the move. The N800 is only restricted by whatever phone you use as a modem.

Also, no physical keypad and no one-handed operation are big drawbacks for me. Dialing numbers or texting without tactile feed-back from the buttons isn't quick.

EDIT: Btw I meant "no physical keypad and no one-handed operation ON A PHONE"