I have heard nothing but positive reviews thus far, and have heard some people say die hard fans of Iron Man will hate on this, guess for me being a die hard fan, I have a very open mind and am willing to accept changes, I realize that translating a character like Mandarin from the comics to a movie screen would be difficult.
In alot of ways what we see on the screen with RDJ's preformance is not really the Tony Stark of the comics, back in the 80's yes, Stark was more smartmouthed when battling his enemies, as the new millinium came along Marvel made him all seriuos and depressing, but I have loved both movies, all the hate on IM2 baffles me, as it delivered what everyone complained about IM 1, more action, RDJ once again delivered an outstanding preformance, as did Sam Rockwell as Hammer, who made that character his own, in the comics Hammer was an 80+ yr old man, who was rather boring.
I get as a fan seeing characters like Crimson Dynamo, Titanium Man, Madam Masque is unlikely, tho I wonder if this movie makes the insane amount of money its projected, how can they not be tempted to make a 4th installment, to me, seeing 3 awesome films with characters I grew up reading, and being a fan of has been a dream come true.