I laughed SO loud and hard for the first 15 mins of this film. Then, it stopped. The movie, which was ripe with hilarious 10 second scenelets, got too caught up with the plot "making sense". The running jokes got old. Jack Black was funnier than the rest; Downey Jr was funny in theory - and I get his speech effect - but you could only laugh at a "mumbling-white-guy-playing-a-black-man" for so long; Stiller did his usual bumbling-stuttering character and it was funny at times. Mainly because the premise of the movie (from my exposure to the trailers) was FAR better in my head than how it materialized in this script. Go a little drunk...it can't hurt.
Started slow - a bit too long and the script was pretty ridiculous and sophomoric at times. But when the movie found it's groove - it's really amazing. Don't wait to see this "at home". It is truly the best in the movie theater.