Personally, I loved it. It was very funny, funnier than most comedies, yet it was also a good action movie where Tony Stark, not Iron Man, does most of the heavy lift. There is no writer I can think of, save maybe Quentin Tarantino who could write Tony Stark as well as Shane Black, whose style of humor is so suited to Robert Downey Jr.
The critics who don’t like this movie are angry either that Iron Man is less the focus this time around, or the twist about the Mandarin, they just don’t get it that its really about Stark, the man in the suit and is tailor made for Downey’s unique talents. And it works. The big fight at the end is clearing things for the next one. I was very satisfied.