Just login to Tweetree with your Twitter credentials, and - voilĂ ! - you now have a super awesome, souped-up version of your Twitter account complete with threaded conversations, and the ability to view external media (think FriendFeed convos, YouTube videos) right within your stream. As a Twitter addict, I find Tweetree to be the spiffiest new Twitter toy on the block.
I will never let this replace FF! Although, I have certainly been asking for Threaded conversations in Twitter, FF is where it belongs! Twitter for Broadcast, FF for conversation!
Definitely a good impression. My only beef with Twitter vs. Plurk is that Plurk makes conversations easy, while Twitter has been more of a broadcast medium. When I reply to a tweet, I have to hope that it attaches to the right one. This may make things easier.