I think the FAQ should have some information about what to expect the device to be capable of. Most people don´t know the difference between browser, flash and streaming media version. They will think that a ¨Internet tablet¨ can do what a normal computer does when connected to the internet, but the N800 is not a windows machine so:

question:
Can I watch streaming videos from the net (like youtube or windows media streams)?
short answer: No, not very well.
longer answer: not as easily as on a computer. The buildin flash player is only version 7, a lot of flash video sites require flash version 9. Also the flash player is rather slow, so youtube is jerky .Speed problems when playing youtube videos can be overcome by using Orb 2 to re-encode the streams in realtime to Real media (supports higher bitrates), but this requires a fast computer and some people reported stability problems.
if you install Mplayer you can watch windows media (and also quicktime), but the bitrate of most broadband streams is too high for smooth playback.
The device does include Realplayer support, but this also has bitrate limitations.
The webbrowser only includes support for embedded Real streams and flash (no windows media or quicktime), and Real is supported by placing a button to launch the external application.


question:
Can I chat with my MSN buddies?
short answer: No, not out of the box
longer answer: you can if you install Gaim with the MSN plugin But A lot of users think Gaim is rather slow. Also I think it isn´t very user friendly compared to the simple MSN clients on modern Windows Mobile devices. (but Gaim does have alot of options)

question:
Can I play online games (javascript, java or flash games)?
short answer: No most games won´t work
longer answer: Java isn´t supported, and the build-in flash player will be too slow for a lot of games. Also a lot of javascript games don´t work in the version 8 of Opera. (the javascript support isn´t good enough on this version)
Most games online are optimized for mouse and keyboard, that the N800 by default doesn´t have, so you will encounter problems because of this with a lot of games.