I'd never watched the cartoon show, although I had a general idea what it was about, and the movie got pretty good reviews, so I put it on my Netflix queue and watched it last night.
I didn't know what to expect, but it's a charming fantasy except for a couple of sappy minutes with Bill Cosby. A girl in West Philly has lost her drive since her grandfather died and she was just dissed at her locker -- the cheerleaders asked her foster sister to a party but not her -- and goes home to watch the Fat Albert TV show and cries. The remote has a magic fit and her tear falls into the cartoon, showing the characters her face. Albert insists on going through the hole to help her and the gang follows, all as humans.
The story helps both the girl and the cartoon characters to learn things, although the cartoons start to fade. Fat Albert risks disappearing all together to make the last push and help the girl.