Hmm.. I have had mine for about two weeks and there are things I like and dislike about it, but before I do a list I just want to say that the n810 is soo darned flexible. I have been able to get it to do everything I need and even improve the performance of the device overall (thanks to these forums). It really is more of a UMPC than a PDA type device. I think i have spent as many hours hacking the device logged in via SSH and VNC as I have on the tablet.

Now likes:
screen
connectivity
open source nature
Battery life

Dislikes:
GPS takes forever to lock in
No scroll wheel or Up/down buttons on screen half (I use it mostly closed)
no built-in cron, xmodmap, and a few other *nix standards.
Not enough RAM/FLASH on the device and the onboard 2GB Storage needs to be at least 4GB.
Needs two SD slots like on n800.

But again, I am amazed by the flexibility of the device compared to its competitors (iPod Touch/iPhone, WindowsMobile) and I love the fact that I am not forced into one carrier, but can tether it to any carriers phone.