Pretty fantastic game. There are many great characters to use and each has their strengths and weaknesses. The costumes are a bit of a let down with many looking outright bad. The good news is that each character has at least one good one with the promise of many more on the way.
There is a very solid single player story that be played through in a weekend, plus many side challenges that take a while to master if you don't want to play online.
As for the gameplay, it's good but not great. If you enjoyed MK you will feel right at home with this game, but the interactive arenas lead to some balancing issues. Coupled with the fact that currently (May 2nd) online is outright broken, there isn't much incentive to competitive play. Though they will most likely patch this.
If you are a DC fan, it would be worth looking into.
If you are a fighting game fan, it is a fair but of fun but some balancing issues mean that it's not going to be the next SF, MK, or Tekken.
If you are a DC & and fighting game fan, Get it, you will love it.