I'm using the latest 3.1 debug version as of yesterday. It fixes a lot of the issues people have complained of in here, namely web browsing performance. I would suggest the average person wait till it's official which should be very soon looking at this latest build. This build is newer than the 3.1 beta from back in august and includes netflix.
I can't post the URL since I'm new but over at gtvhacker in the revue section there is a thread titled "Honeycomb 3.1 UserDebug Leaked!"
How about as a media player? Does Honeycomb address those issue? How does it compare to say Boxee? More specifically, how does it handle 720p or 1080p mkv files? Have you had a chance to try?