I completely love it.
One of the most accessible online games I've played. The graphics are great for the base game being free to play. The story is surprisingly not bad, the voice acting can be funny and interesting. Interface could stand for some improvements, but honestly the native controller support is good and there are solutions provided by the community to add more hotkeys, etc.
I love playing as my favorite heroes. Despite so many other Marvel games coming short, this game provides the most satisfying incarnations of Iron Man and Captain America - which is pretty incredible considering both of those characters had major console game releases (two of them, in the case of Iron Man) that don't measure up to this.
I'm sure there are veteran players who are more jaded and have had time to see the flaws that I haven't, but I just wanted to share that as a new player, I couldn't be more happy to have started playing this game.