Wall-E is not what most people expect it to be, I believe. There is a heavy moral/political message in the story that viewers may not be prepared for. The movie's slow start may lose a few that are not lost later by the message. The animation and effects are stupendous - it's the story itself (the obvious and the subliminal) that requires careful consideration. And by the way, the robot "love story" is way cute.
I was a hero for taking four of my grandchildren (ages 4, 5, 8 and 11) to see this movie. Nobody took a nap during, and everybody talked about it for hours after. The animation is superb, the colors are vivid and the storyline is inspiring to adults and easy to understand for kids.