From Madman in Japan:
It's still been under half a day since the update came out so there's not much details yet. I'm assuming that SNKP might make an announcement to the general public on their blog today.. if they're competent.
According to some early reports, the bugs and infinites have been taken out (say goodbye to the massive Mature population). The roll HD has reportedly been taken out. Players are saying that there doesn't seem to be any balance changes?
I probably won't have time for hands-on until the weekend.
Still no announcements on the Official KOFXIII blog regarding the update yet, so will have to wait to see what the exact changes are.