When making a game with established characters the single most important thing is making sure the player *feels* like those characters. The Arkham games were great beause of what every reviewer said- they made you feel like Batman.
This game gets this right, every character I played felt right. I haven't played all of them, there are 100 characters here. Actually more when you remember that are a few cases where the same character has multiple movesets, such as Jean Grey and Phoenix. But they all felt right and I had a massive smile on my face the entire time I was playing this.
Sure, balance in this one can be a bit rough at times but I don't think it matters if Magneto is more powerful than Black Widow, because playing Magneto makes you feel like Magneto and playing as Black Widow makes you feel like Black Widow.
With the remakes in the archive there is also a crazy amount of content in this one to.
This game is just really great. Highly and strongly recomended, especially to fans of Marvels comics, tv shows or movies.