Robert Downey Jr. looks as hung over in “Iron Man 2’’ as he seemed drunk in “Iron Man.’’ He does his share of drinking this time, too. And the sequel makes more out of his insobriety. It has an early stretch where it fizzes and slurs, with the stars stepping on each other’s lines and feet. The movie feels drunk, too.
Downey’s billionaire military-industrialist slut, Tony Stark, slams down into his own expo (for both peace and state-of-the-art weaponry) as his ironclad superhero self. The elemental casing falls away, revealing a handsome pinstripe suit. Tony pats himself on the back for saving the world (“I’ve privatized peace,’’ he brags), praises the scantily clad entertainment (hey everybody, it’s the “Iron Man 2’’ dancers), then finds himself served with a subpoena to testify at a Senate committee hearing, where the movie begins its improvement of the flagging after-party atmosphere of the first movie.