I picked this up day 1 and I'm enjoying it as well. The single player is indeed shallow. I do like the quick battle mode as there's different variations of AI, but the story and arcade modes are weak. For arcade, all it is is 6 battles, and there isn't even a speck of story like past SC arcade modes.
Of course, the online, it's as smooth as a baby's ass. I haven't tried the global coliseum mode yet, but I've had practically no problems in ranked and player matches other than when my net decides to be unstable. Plus the lobby system in player matches is cool. Up to 6 players and when 2 are playing, the other 4 get to watch. With the winner continuing until somebody can defeat him.
Edit: Also, not sure if it's just me or not, but it seems like some of the characters are easier to get into this time around. I remember struggling to use Hilde at all and while I'm still not good with her, she at least seems easier to use.