A good quality game, but not amazing.
The game is classed as a "Action RPG", but really it is more like a "beat 'em up" which choice of permanent power ups. You basically develop your character, but "learning" a choice of skills, each character with their own set of skills and special power ups and weapons. There are enough variety to make each different character unique. The single player game will keep you occupied for about 30 hours, and the story is your average "bad guy wants to take over the world/universe", however, the story is detailed enough to be much better than you common Hollywood production.
You will find all the favorites of the Marvel universe in the game, with a lot of "lesser" known heroes and villains. It has to be said that it seems like Marvel did a shameless plug of some of the lesser known characters to give it more publicity. For the gamer it means you can play some of the lesser know cool heroes not found in other games.
Game play: The game play is easy to master and the should be only a short learning curve. However, it has to be said that MUA (for the PC) was developed with consoles in mind so some of the controls are much more better on the consoles. This is not a major drawback but it does mean that the controls could have been better if it was designed for the PC. Another problem is the camera which sometimes get stuck, and the view gets blocked by a wall in front. This does not happen very often but annoying, especially with you are in the midst of battle.
Graphics: The graphics are excellent in the sense that you feel the comic book heroes coming alive, but in terms of games of today, it is not really amazing (just good). The animations are varied and smooth and all the characters have detailed models. The backgrounds are very well done, and looks like the developers have really made an effort of translating the comic book 2D to the 3D of the game. Marvel fans will fan lots of easter eggs in this game.
Sound: A lot of people reading comics will imagine what each character sounds like, and which means that if the voices does to match the preconception, they sound funny or stupid. However, you cannot judge a game because Marvel or developers used a different voice. This aside, I can say the sound is of good quality, and the voice acting is not dull (monotonous). However it is nothing amazing or memorable.
AI: This is a multi-player game (even single player), where you fight as a team of four. The other three are AI controlled in single player game. Although AI is not especially important for a beat 'em up, your other three members (which should be props), sometimes tend to get in the way, which is annoying. I do not mind them being props but when they affect gameplay, you have to knock some points off. This is not a serious issue, and in general you will not have much problems.
Multi-player: This game, has lots of things to do in single player, especially with all the Easter eggs, but it is more fun when with multi-player. This is especially true because, without multi-player, you will just be easter egg hunting. Character development for this type of game is shallow, so there is not big incentive to improve your characters too much. I cannot say too much against multi-player except it makes the game a bit more fun. The only bad point about MP is that there is one host, and other players play the characters on that host. This means that if you are not the host, you will be playing one of the other three characters, and helping them level up instead of using your own characters. This is a bit of alet down, because why waste your effort on other peoples characters.
Overall: This is a great game, and quality production. If you are a Marvel fan, needless to say this is a must. If not. If your are a beat 'em up fan, this is also quite good. This game is also a good recommendation for people who are interested in beat 'em ups, but do not know which one to buy. It is a really nice game to have in your collection and most people, even non Marvel fans will find it fun.