You don’t go into a movie like Iron Man 2 expecting greatness. It’s graded on a curve.

Does it make you laugh? Excite you? Show you things you haven’t seen before? Does it make for a diverting two hours away from the summer sun?

Iron Man 2 does most of those things but it doesn’t do much else. It’s a hodge-podge of ideas and characters that never coalesce into anything meaningful.

This isn’t always the case with sequels, particularly comic book sequels. Superman II raised the stakes of the first film, introduced three formidable villains and stripped Superman of his powers as it developed his relationship with Lois Lane. Spider-Man 2 was a major improvement on the first film, with Alfred Molina’s Doctor Octopus as the perfect foil for a maturing Peter Parker. And The Dark Knight built on the solid reboot of Batman Begins and, thanks in large part to Heath Ledger’s iconic performance as The Joker, emerged as a visionary masterpiece of a gothic crime movie.

Iron Man 2 doesn’t try to do any of that. It plays more as a set-up for future sequels and spin-offs (The Avengers and Thor among them) and as an excuse for some scenery-chewing by an assembly of fine actors.

I was initially wary of this movie because I suspected the filmmakers had stocked up on villains and sidekicks under a misguided “more is better” philosophy. But that suspicion was unfounded.

In fact, my chief complaint about Iron Man 2 is that we don’t get enough of the villains. Sam Rockwell, as always, steals the show as Justin Hammer, a weapons manufacturer jealous of Tony Stark’s success. And Mickey Rourke brings nuance to Ivan Vanko, the Russian physicist/psychopath who becomes Iron Man’s biggest threat. I wanted to see more of both of these guys.

Working for the good guys are Pepper Potts, Stark’s assistant and love interest, played well by Gwyneth Paltrow; Natalie Rushman, a new hire with a mysterious background and the curves of Scarlett Johansson; and Lt. Col. James Rhodes, military man and Stark’s best friend, played in this film by Don Cheadle, who inherited the role from Terrence Howard.

All three acquit themselves well, especially Paltrow, who plays well off of Robert Downey Jr. — these two have the sort of real chemistry you usually don’t find in comic book movies.

As for Robert Downey Jr… he was born to play Tony Stark, the egotistical man-child who saves the world mostly because it looks good on him. He is the rare superhero who provides the comic relief in his own movie and as always he commands the screen (though his facial hair is distractingly over-designed).

So yes, the parts are all in place, but the story doesn’t live up to their potential. Stark is fighting two enemies here: his own mortality, in the form of a depleting supply of power to his chest battery; and the scramble by the rest of the world to develop technology to match his Iron Man suit, most successfully by Rourke’s Vanko. Neither of these storylines provides much dramatic heft, and both are resolved quickly and lamely.

We’re left to enjoy the film for its smaller moments… a fight between Potts and Stark interrupted by a rotating desk ornament, Downey’s exchanges with his computer J.A.R.V.I.S. (again voiced by Paul Bettany), Sam Rockwell delivering an inspired monologue about a suite of high-tech weaponry.

There is a lot of talent behind this movie, and they appear to have had a lot of fun making it… it’s a pity it ultimately amounted to so little.