Bought it the other week, same here expectation 5/10 overall 10/10...
Saw it reviewed in some free supplement in one of the Christmas papers and they rated it as the best DVD of the year 2004, as to be the best DVD it MUST have great extras. Boy does it, the extra features on the DVD are worth the money alone; extended scenes, outtakes, video diaries, comic strip explanations of the plot holes, extra footage they shot, interviews, making of... I spent as long if not longer watching the extra bit as the film... the way DVD should be
Oh, and the film itself is hillarious