A slight improvement over the original game
In the first game one of the most problematic areas of the game was the flying game mechanic. Iron Man 2 was given an overhaul in this area. Now the controls for flying are more akin to an Armored Core game and it works much better than the first game. The controls are still not precise enough to navigate an exhaust vent, though the game will make you do it anyway. The flight controls work ok in the more open environments where running into walls is not an issue.
Iron Man himself feels stronger than he did in the first game. He can take care of weaker enemies easily and the more powerful enemies can be dispatched with finishing moves. Iron Man and War Machine's suits can be upgraded with a light RPG type upgrading system. However, the upgrades cost a lot of mission points (points acquired during missions) and don't seem to really do very much.
The environments are also destructible this time around, which adds a little bit more fun to the game since you can blow up buildings and other junk that's lying around.
However, the core game play in Iron Man 2 is still just plain boring. Missions are very similar and the action is too repetitive. The combat is so simplistic that it devolves into button mashing to dispatch foes whether you are using melee or ranged weapons. Also, the unlockable suits seem really counter productive since only two of the suits are actually better than the suit that you start out with.
Overall, this game is a slight improvement over the original game. If you are really into the Iron Man movies you might find enough content in this game to keep you entertained, but this game still has a long way to go to be a game worth playing.