Hey there Sach!:) Long time no see, haha! Ok, back to topic:
I went to check the beta forums and noticed the following (note: I'm not sure if all of them have been listed already.)
1. Signatures: Signatures don't show in the posts, as of yet, of course. But one thing I must say, I like how user-friendly the beta forum is.
2. Text formatting: As of now, there isn't much text formatting in the beta forums, especially the missing of the oh-so-popular BB code button. Some things like Twitter button, finding, replacing and going to is missing in the text formatting!
3. Some little confusion with the comment system: I mean, the UI is great and whatnot but one thing that stood out the most was upvoting and downvoting, I think reputation mode is better (I think I'm biased though).
Yeah, that's it. Great job with the beta forums! It will take quiet a while to get used to it though!