I thought it was a mixed bag. The first half had a lot of awkward moments with jarring tonal shifts. I felt it needed the confident hand of a more experienced director. The second half was better, good enough that I'd rate it over Iron Man 2, but not the first.
BIG SPOILER!!!
While I appreciated the twist with The Mandarin on a storytelling level, it was kind of a waste of Ben Kingsley. He's a great actor and made that villain so compelling and believably scary, that to have him be a hoax felt like a let down.