Movie sequels are funny things. With very rare exceptions (Aliens, Terminator 2), quality goes steadily down as the number goes up. Superhero movies are especially prone to this because of the pressure to continually raise the stakes. Superhero movies are spectacle movies, where larger-than-life heroes battle outrageous foes to prevent huge catastrophes. If the hero saves a city in the first movie, then naturally in the second movie he must do something grander - save a country perhaps. If the first movie had a great villain, then why not add another to the second? This (and lousy, lazy screenwriting) is how we go from the 1989 Batman to 1995's Batman Forever and 1997's Batman and Robin. Marvel movies are hardly exempt - X-Men 3 and Spiderman 3 come readily to mind.
How, then, does one avoid tumbling into bat-nipple territory? By sticking to good storytelling principles, and by understanding who the characters are, and that ultimately the story is about them. Iron Man 3 has flaws. I'll get to them later. It's a good movie, though, and it's good for very simple reasons. The most obvious that Robert Downey Jr is perfect. Tony Stark is egotistical and brilliant, but also scarred and vulnerable, and Downey nails it, and he does it with style. The writers also nailed it, giving him the witty lines in which to infuse his charm.
The choice of plot is equally important, though. There are, of course, huge, over-the-top, action sequences, and they are generally quite well done. But the plot is personal. The opening voice-over explicitly states that this story is about demons, the ones inside and the ones you create. It's a story where the stakes are high, and the fate of nations is in question (more or less), but it's also intimate - the story of individuals and the choices they make, and the consequences of those choices.
This is a darker movie than I was expecting. There is levity and banter, but also a grimness, a grittiness. I don't mention that as a positive or negative, just as a thing that is.
Possibly the best scenes in the movie are those involving the interaction of Tony Stark and a boy named Harley.
I mentioned flaws. The worst is the nature of the bad guys. Without spoiling anything, I felt that the capabilities of the antagonists, while draped in science-colored cloth, were really magic. It may seem odd to complain about lack of realism in a universe that also includes Thor, but Thor isn't in this movie. Iron Man is a technological hero, and while the science of his suit is also wildly improbable, it's still far and away more plausible than what the bad guys have going here.
My other complaint is that the final set-piece, in addition to being partially spoiled by the trailer (again), and despite being well-staged and generally exciting, lacked a certain amount of real tension. The parts that involved Stark himself were good, but in other areas the scene seemed to trivialize certain aspects of Iron Man.
Was that vague enough?
Bottom line: good action movie with witty banter, oodles of charm from Downey, and a solid emotional grounding. It's better than Iron Man 2, but probably not as good as the first - it's pretty hard to beat the
character introduction/origin story. It comes second on my list so far this year.
2. Iron Man 3
3. Jack the Giant Slayer
4. Beautiful Creatures
5. Oz the Great and Powerful
6. G.I. Joe: Retaliation
7. Hansel and Gretel, Witch Hunters