I got my n810 about 12 hours ago and love it.

Faves:

• The Screen (the best I've seen on any mobile device)
• The Keyboard
• The Browser
• Canola
• FBReader
• GarnetVM (my contacts and memos are now on my n810)

Problems & annoyances:

• GPS is slow (but with a-gps, not horribly so)
• Linux is still an alien country to me, but one I'd beginning to learn a bit about.
• The n810 requires a mixture of touch, stylus, and keyboard to use, and while I don't find that particularly hard, it would be nice if it were a bit more finger friendly.
• A caps lock button would be a vast improvement

Also, the wifi is stronger than the one on my laptop, which is very nice indeed.