No usb port so can't connect keyboard, external dvd player, camera, camcorder, ipod, mp3 player, usb headset......
Doesn't support Flash, so no gaming or video
No card reader, so you can't see your photos
No camera or webcam
Doesn't support multi-tasking, so does one thing and one thing only at a time
The worse thing for me is the size and shape. It's too big to operate with one hand, you have to use two hands to watch a dvd unless you either prop it up or sit hunched over your lap.
If you carry it about you will need some kind of cover, otherwise the screen will get scratched.
It's too big to slip in your pocket.
I'd much prefer a fully functioning netbook, which is just as portable but far more practical.