It's rather impossible to tell the subject of the film in 1 or 2 sentences. It's the story of two monsters, a parallel world, an adorable little girl and an accident that generates a screwball comedy, with lots of action & fun.
Nominated for 4 Oscars:
Best Animated Feature
Best Music, Original Score
Best Music, Original Song (WINNER)
Best Sound Editing
This one lost Best Animated Feature to Shrek. And although Shrek is excellent, I'm not sure it was the right decision. Monsters is surely one of the top 5 best animated films this decade has given us (and that's saying a lot considering Nemo & Wall E). It's so much fun, the story is very very creative, the voices fit perfectly and I loved the mixture of sweeeeet and smart.
The technical part is flawless and the rollercoaster-like scene with all the doors is a classic chase scene "filmed" perfectly. Lots of colors and an adequate ending.
On an animated features scale, I'd probably give it a 10/10. But putting it in line with motion pictures, my rating for the film is: 9/10. Yet, make no mistake: Monsters, Inc. is from now on in my Top 100 favorite films EVER.