The N810 is a very good device.
I use it every day, much much more convenient than my laptop to do some IM, quick web browsing and checking mail.

I'd say the main concern is its GPS time to first fix. It has improved a lot with A-GPS lately, but if you don't have this data available, it takes from minutes to forever to get the fix.
But once the fix is done, it works perfectly, we can even say it's very robust.