I got the Japanese version this morning. The game is indeed everything you're expecting...as long as you make peace with the fact that it's on a portable. The D-pad is in an odd place, and takes some getting used to.
Online IS 60fps in 2D mode! ...assuming your connections can handle it. I can only find matches within Japan, so I can't yet comment on worldwide matchmaking.
Why you would ever play the game in 3D mode is beyond me. I tried it and lasted about half a match until I slid the slider back to 2D...and it transitions without a hitch.
God damn this game is good. This makes everything else that's come out for the system (save for SSF4) look pathetic. There are a ton of unlockables in the game, and for those worrying about language issues, the Japanese one let's you turn everything to English if you'd like.
Now if you'll excuse me, I've gotta get back to gettin' my ass kicked online.