This is a movie worthy to be called The Simpsons Movie. It goes back to the glory days of the earlier seasons. The jokes are very funny and the performance of all the voice-actors is great. Especially Julie Kavner was fantastic as the voice of Marge Simpson.
There a lot of characters that unfortunately did not get into the movie, or their performance was only a few seconds long. But with a cast of hundreds of characters accumulated over 19 seasons (at the time when the movie came out) its only natural some didn't make the cut. Still, its a shame we didn't see principal Skinner or Sideshow Bob on the big screen.
A lot of cultural references were made into the movie including: Lisa's lecture, An Irritating Truth from Al Gore's documentary, Homer who plays Grand Theft Walrus, from the video game Grand Theft Auto and off course Spider-pig from the movies and comics Spider-man.
If you love the earlier seasons of The Simpsons than you should definitely see this movie. I never had the feeling that i was just watching an extra long episode of The Simpsons, the makers put a lot of work in this movie and it really shows.