"Pixar has done it again!" I think at this rate that's going to become every reviewer's favourite catch phrase.
The animation is in "Monsters, Inc." is fantastic, although it doesn't feel the need to tell its audience "look! this is amazing, never-before-seen-animation!" every five minutes. It carries the story, makes it totally believable and only at the end of the film do you realize it was absolutely flawless.
What truly sets a Pixar film apart though is the story and the characters. "Monsters, Inc." is different in tone to their previous film "Toy Story 2" or to "Shrek" which everyone seems to keep trying to compare it to. It doesn't have their self-referential pop culture humour but personally I don't think it lacks anything because of it.
For one it has Boo -- in my opinion the cutest little girl that's ever been animated. The stuff with her, Sulley and Mike is absolutely priceless. A great deal of the fun in this movie is based around these big 'scary' monsters running in absolute terror of this tiny little girl. It's not high brow but it is hilarious.
And Monsters, Inc. has heart. Lots of heart. The bond that forms between Sulley and Boo is beautiful and surprisingly powerful. I really commend John Goodman on his wonderful voice performance as Sulley the gentle beast. Plus, if there was any danger of this film slipping into the overly-sickly-sweet area, we've still got the razor sharp wit of Billy Crystal as Mike to reign things back in.