This film is sorely under-rated both here and IMDB. It is hard for comedy films to connect with a wide audience especially when there is a lot of swearing, sex and drug references as this can alienate a large portion of the audience. Fortunately I love swearing, sex and Drugs, however not specifically in that order.
This film is based on Brand's character from 'Forgetting Sarah Marshall' which is also a great film, but 'GHTTG' has a darker feel, a kind of 'gross-out' comedy without all the 'gross-out', and instead genuinely smart and funny dialogue. Jonah Hill is great as usual and Russell Brand delivers another brilliant performance; however I doubt the role was too much of a stretch for him. The film also has many cameos from some very surprising names as well as an excellent performance by Sean Combs, or P-diddy as he is known to his friends.
This film might not be for everyone, I guess you either love it or you don't, it's all down to your sense of humor. Personally i loved it. This film has some of the funniest scenes I have ever seen, the last movie I saw that really tickled my funny bone in the same way was, 'Deuce Bigalow - European Gigolo', I guess that more about me.