Visuals are pretty key to any movie-tie in and Ratatouille does a fairly good job considering the PSP's capabilities. Both levels and in-game characters are a bit angular, but are by no means bad. Having played the 360 version of the same game (well not the same game, but the same license), it is kind of hard not to notice how much better the non-handheld version looks; but like I said, Remy, Gusteau and the other rats still look pretty good.
Sound isn't bad at all. Background music tends to be a very soothing, French influenced violin tune while the different sound effects get the job done. The voices aren't all that bad either. The two more vocal characters in the game, Remy and Gusteau (who acts as the game's hints system), both come through loud and clear.