I just saw the movie, so let me address the critics.
1) Bawww, the movie didnt have as much humor as the first one.
Well its a sequel to the first one and it has its own story. Tony is slowly dying FFS! If you want a comedy, watch Wedding Crushers or something. What was the movie supposed to do? Have Tony laugh and blast things for the whole movie? The whole subplot about him dying for really good imho. It was one of the backbones of the movie.
2) It didnt have enough action.
I dont know about you guys, but the whole movie flew by pretty quickly and it had enough action scenes. Yeah, both the Monaco and the final Whiplash battle were short, but we also got Rhodey vs Tony and Natasha vs guards. TDK had more action because it was 2.5 hours long!
3) It wasnt citizen Kane or TDK.
Yeah ok, it wasnt. But it was a comic book movie. If this story was printed as a comic book, it would have been a good one. Hell, Extremis is considered a great IM story and it was basically just like IM2 and the villain was an ***hole with superpowers!
The sooner people realise that Marvel is just producing comics book stories on the silver screen and is not trying to do DEEP movies, the sooner they'll sit down, eat their pop corn and enjoy the movies!
And i'm gonna get flamed for this but i never saw what's so great about Spiderman 2. He was doing OK, then he lost it then he got back and won the girl. His powers which come from his enhanced DNA didnt work because he was sad (you get your myopia back because you're sad?) and Otto was also talking to his tentacles

. It was a good SM story but it wasnt "OMFG MASTERPIECE"! In my humble opinion Ironman 2 was Tony's Spiderman 2. He loses it, he gets back on his feet and he beats the villain. It just didnt have the goosebumps inducing inspirational speech from Aunt May that gave SM2 more drama.
4) Too many characters.
The major characters were Tony, Vanko, Hammer and SHIELD (Fury + Natasha + Howard Stark) and Rhodey. Those were the major characters. You should look the Shield agents as one character, looking over Stark. What more did you want to see from Fury or Natasha? Their childhood? They came and helped Stark. Did you get Maroni's background in TDK?
Rhodey had enough time to show us his mixed feelings and regrets and being the true friend that will give you some hard love when you need it.
Hammer had more than enough time and was fleshed out well.
Pepper had enough time as well. What more did you want from her?
Only Vanko didnt have enough time and even the time he got he wasted it by speaking in Russian (which at least in my theatre wasnt translated so i dont know what he was saying). Maybe he was pretending not to have difficulty in English so that he could create the whole drones vs pilots misunderstanding with Hammer. But I wanted to see him do more than work on Hammer's drones and the talk with Tony should have been longer somehow. But it was good nonetheless, i loved the "sharks will come" bit, it made the dialogue more iconic.