I've played DC Universe for PC. Not PS3.
Besides the Heroes focused portion, Marvel Heroes is VERY different than DC Universe.
DC is more like WoW.
Marvel is more like Diablo.
DC you make a hero/villain who takes orders from Batman, Superman, Joker etc...
Marvel you actually play the hero. Don't think you can play villains.
they were very smart to go with diablo style IMO for this game, this way there is no direct competition with DCUO