It's really not all that bad.
I hate Iron Man, due to the way Marvel Comics raped his character during the Civil War story, but the movie made me give him another look, and my general dislike for him changed to a more... respectful toleration.
The movie, I actually loved. I loved it so much, I, perhaps foolishly, threw down the cash for the Xbox 360 version of the game.
At first, I was shocked by the clunkiness of the control scheme. Running in the sands in the Mark I armor was rather uncomfortable, but in a few moments, it became second nature. The first level feels pretty good just running around, fighting the horde of mindless enemies.
Then comes the Mark II Armor, and things become a bit more complicated. It took a few moments to acclimatize myself to flying, as I would become disoriented every single time I tried to take off. The camera jerks rapidly, and if you are trying to take off and maneuver at the same time, you will probably hit something. The trick is to just relax and hit the button, he'll lean forward and take off, and I have found that flying around is quite fun, and not difficult in the least. In fact, much like web slinging in the first Spiderman game, it is fun and peaceful. Once you have the knack for it, the flying is no problem at all.
However, you won't have much time to enjoy the flying with the maddening difficulty leaps in the game. Being tailed by 8 missiles while trying to fly to safety, fight off several tanks and turrets, and complete a mission in a certain amount of time is a definite challenge. The game is not broken, just hard in areas. With the wrong armor set up, the difficulty ramps up even more. You have to be on constant guard, and use split-second timing to dodge the missiles, but once the player is familiar with the controls, they shouldn't have too much trouble.
The enemies in the game are ridiculously stupid, but the overwhelming numbers make them quite lethal. They are stationary, except for the jet fighters, but their fire power makes up for it. If a player isn't careful, then they will die quickly. It is easy to get carried away against the lesser enemies, as the feeling of invincibility waxes and wanes, so keeping a constant eye on your life support system and radar is very necessary.
There is a fair amount of customizing in the game, and in general, it tips the scales in places. As was mentioned, the gatling and meson repulsors, Iron Man's standard weapons, either fire quick and weak, or strong and slow. The various armor set ups are up to the player, and I have found little problem with them. The first level Gatling repulsor barely eats away at energy, but the advanced version will until your power systems are upgraded enough to counter the energy drain. It's all about finding the right balance for your play style.
The unlockable armors are fun, but they cannot be upgraded, and the fact you cannot use them in the main game almost kills their purpose. Still, it is interesting learning how they all perform.
The graphics in this game are quite good, with most of the detail on Iron Man himself, and all the enemies looking adequate for their roles. The levels are massive, and are generally plain, but it is still impressive flying around them and feeling so small and powerful in the great big, bad worlds. If a character chooses to let nuclear reactor melt down in one level, the fallout covering the area gives the whole level a different, eerie look. It is quite impressive, but I wouldn't recommend letting it happen.
The cutscenes look good, but only visually. The animations seem bizarre and inhuman, but the voice acting is top notch, especially from Robert Downey Jr.
With a little bit of practice, this game is not half as difficult as many people are making it out ot be. It is challenging, yes, but not impossible, you simply have to think about what you are doing at all times. I think due to the frustration factor of this game, many people are giving it a bad review, and granted it needs a bit of work, but it is a fun, challenging experience that delivers that feeling of being a one man army.
+ Great voice acting
+ Varied missions, and optional side missions.
+ Customizable armor
-/+ Decent Graphics
-/+ Interesting but almost pointless unlockable armor
- Steep Learning curve
- Strange cinematic animations
- Frustrating difficulty spikes