I tried all 3 beta's they had out, each one less buggy then the previous. I have downloaded and installed the release version and the small problems i've found:

It does in fact load noticably slower than the 2.x versions

With associations, I prefer to use winamp for all Audio file and wmp 6.4 for video. For some reason if I try to change the association for mpeg/mpg, it also changes it for mp2/mp3 and vice-versa .. so either wmp or winamp controls all of them
(well upon writing this I just doublechecked this and what I did was un/reinstall winamp3 and during setup, tell it NOT to associate video files with itself and unchecked it's feature to keep file associations even after othe programs "steal" them. All seems well with this then)

A minor feature not found in 3 that was in 2x was SHIFT-V (stop with fadeout) and I think most of the other keyboard shorcuts. Not a big deal, but something I kinda liked when turning off a song.

I do however like the skinning and media library and a something similar to the fadeout to stop is the new crossfader between tracks.