I second alpepper's judgement: Ratatouille isn't Pixar's finest, but it's still quite entertaining.
SYNOPSIS: Rat with enhanced senses dreams of being a chef. He gets his chance by meeting a clumsy dishwasher. Insert typical buddy movie story here, complete with chick coming between the friendship.
PROS: While the scenery is not as dazzling as its predecessors (like Finding Nemo), the setting doesn't lend itself to that atmosphere: Rats aren't particularly "pretty", and kitchens aren't entirely glamorous. But, what you will notice is the fine attention to textures in the rendering: Rendering believable, animated fur on an army of rodents is no small task!
CONS: Storyline is very predictable. But, then again, it's a kid's flick. What do you want?
OVERALL: Very endearing, though probably will fade in the background when compared to other Pixar films.