The Simpsons Movie is fun film to see if you don't have anything else to do…otherwise it isn't a movie I would recommend you spend lots of money to see. The jokes aren't very good, at least they aren't much better than the show and the story line is ok, but a bit obvious. That stuff aside, I did find it a very entertaining film and seeing it with friends always helps it to be more enjoyable. There are a few good laughs mainly to do with Homer - I found his expressions part of the funniest things in the film - however, I think that most of the funny moments were in the trailers. I like how the movie starts in a TV ratio and then it opens out to widescreen.
It is one of those movies that the more you watch it, the more things you realise. For example, when Homer is nailing the tiles onto the roof with Bart, I wonder how many of you realised that Grandpa was reading a book called "Oatmeal for Enthusiasts"? It is these smaller things that are often the more funny. There are some parts which push the boundaries of a PG film including the sequence when Bart skateboards to Krusty Burger naked. It is funny, however, because it catches you off guard and you don't expect what is about the happen (I won't say what happens in case you haven't seen the film)
Simpsons fans will definitely enjoy this film and I did myself, however I wouldn't buy it on DVD until it comes out as an ex-rental.
