I don't think I've laughed watching a Harry Potter film so much. From the many love triangles (and love potions) between Ron, Lavender (Ron's snogging partner), Harry, Ginny, Dean, Hermionione (and her very cute but obsessed gent), I think it was a brilliant plan to lighten up the movie and prepare all of us who love the book for the very sad ending.
All of the action and central plot points are hit, including the very important stuff. As a bonus, Tom Felton was given much more of a chance to show that he is good actor, as did Daniel Radcliffe.