In a world where sequels come in two flavors... this sequel does not really break the boundaries. Seriously, though, as we all know, there really are only two forms of sequels: everything the same but more (a la Alien to Aliens) or everything the same but different (a la Predator to Predator 2). While Iron Man 2 may seem like its a case of everything the same but different, it is more a case of everything the same but more.
Why do I say this? Well they both start off the same: Tony is high on life, on top of the world, and the man to be envied (Iron Man he is showing off his Jericho weapon and making money, Iron Man 2 he is showing off his Stark Expo and making money), but he has a problem (Iron Man he is captured by terrorists and given super pacemaker, Iron Man 2 he is captured by congress and is poisoning himself with super pacemaker v3.1). Things start looking up (Iron Man Tony escapes from evil terrorists, Iron Man 2 Ivan Vanko is arrested), but wait, there are more problems (Iron Man Tony announces no more weapons programs, Iron Man 2 Congress announces no more Tony Stark). Relationships become strained (Iron Man Tony fights a group of mean terrorists and alienates Rhodes, Iron Man 2 Tony throws a party and alienates Rhodes who becomes Warmachine and kicks Tony's butt). Corporate skullduggery commences (Iron Man Obadiah Stane starts pushing Tony into a corner in the boardroom, Iron Man 2 Justin Hammer begins backing Tony into a corner with his Vanko designed Droid army). Ooooops wait, Girl saves the day (Iron Man Pepper Potts figures out skullduggery and brings SHIELD cavalry, Iron Man 2 Natasha Romanoff figures out Hammer's dumb plan and brings Happy Hogan for whup-ass session), but Iron Man must fight his foe (Iron Man big battle with Stane, Iron Man 2 big battle with Vanko and Droids). Iron Man wins! Roll Credits.
Yes, it seems like the film was an exciting rehash of the first film, but for some reason, it works pretty well. You have a lot of the elements of 'the same but more', but the slight variances in the story make the film much more interesting. The hordes of Hammer Droids make for a slightly different feel to the story, but that is alleviated by the introduction of Warmachine, who offsets the villains' numerical advantage. While I would not say that the second is in any way better or more entertaining than the first film, it certainly is more. More explosions, more action, more romance, more technobabble, more Sam Rockwell, more villains, more drunkenness, more girls, more characters, more subplots, more Samuel L. Jackson, more shots of Robert Downey Jr's chest... OK, so it's not all good stuff. The way I look at it is Iron Man 2 is to Iron Man as Batman Returns is to Batman.
Obviously an action packed crowd pleaser, this is a pleasant way to spend an afternoon without having to think or figure out stuff. Pretty standard action movie fare, though I will admit to liking the original film better.