The only people who love this movie are those that are easily amused by the Simpsons. The movie is no better than regular episodes. If you have ever watched an episode and found a portion of it lame, you will feel that way about parts of the movie.
Its an 86 minute movie. So it'll go by fast. Depending on what you pay, consider if its worth your 9 or 10+ cents per minute.
Personally, the pig stuff is incredibly lame and annoying. Spider pig obviously is as dumb as it comes. This is humor that a 5 year old can do better with.
The Alaska scene in the movie is quite pointless and Homer dogsledding is of no interest to me.
Recycled ideas of Bart under Flanders guidance, Springfield's environmental disaster, Homer adopting an odd pet (helper monkey, lobster, now pig), the Simpsons being forced to flee town. Snooze.
Lisa chunk of the film tries to set up the story, but the involvement of the Irish boy was meaningless.
For the most part the gags are fairly flat. I won't say I didn't laugh, but I would put the ratio at about 1 in 6 for anything good.
The last 20 minutes is pretty dull. The first 20 minutes is reportedly the best.
Waste your money if you want, but you probably should just wait for a $10 DVD to come out.