There's nothing I hate, but there are one or two points which could be improved.

Hardware controls for media player while the screen is off would be nice. If I'm in the gym it'd be nice to be able to have hardware forward, back and pause/play buttons so that I don't have to take the n900 out of my pocket. I'd suggest the volume buttons for back/forward and the camera shutter button for play/pause.

Quite frequently I leave my house early (05.30 to 06.00) to get to the gym before work. If it's a long day at work then I can run out of battery power before the end of the day, so a little more battery life would be lovely, thanks.

All in all I've been extremely happy with the n900. The only other way to improve it would be to ship it with a case of beers!