This felt very underwritten, like they had an outline and filled in all the bits saying "Action sequence here" but missed 3/4 of the "character development here" and "joke here" bits. I was worried that the casting of Don Cheadle meant Rhodey wouldn't be funny any more but NOONE was so it didn't make much difference.
Also I think the writers missed the bit about Tony being to some extent a morally ambiguous prat you enjoy watching but don't
entirely like, and the bit where the moral of the previous film wasn't actually "YAY CAPITALISM WOO GUNS".
Not spoiling anything not in the trailer:
On the plus side, Scarlett Johansen's character and Pepper spent the whole film being self confidently competent and kinda femslashy. I found myself liking the villain Victor (alas Sam Rockwell's character was irritatingly dull), possibly because he was the only person in the film who wasn't 100% in favour of the American military industrial complex (admittedly for not very deep reasons) and Mickey Rourke managed to exude such an intense aura of patient thuggish disdain he somewhat overcame the silliness of the film around him. Plus they were so squeamish about violence I'm not sure he actually ended up killing any totally innocent people (he gave it his best shot, mind you, he's not a nice guy). And he likes Australian native birds! :)
The one thing in the film that genuinely offended me was the physics. Just..what. No. Even by the standards of this sort of film. (nb many other things offended me too, bit I was expecting them more. Russian stereotypes ahoy!)
( And now for spoileryness )