It's like "After Hours" on laughing gas. All three leads get their fare share of funny moments, but make no mistake: Galifianakis is the breakout star. It's the kind of fully committed, no-vanity comedic performance that deserves to be recognized with an Oscar nomination, even if the Academy is too square to realize it.
The unrated DVD runs about eight minutes longer than the theatrical cut, but this is one case where the scenes deserved to be trimmed; they offer no additional laughs. The same cannot be said for the 100 extra photos; you'll understand that once you see it. And do not bypass the gag reel, with some laugh-out-loud insult improv between Helms and Galifianakis.
Much like director Todd Phillips' "Old School," I suspect "The Hangover" will hold up quite well on repeated viewings.