We saw Ratatouille last night at the drive in. Whether you will like it depends on what you like in a movie. If you or your kids prefer non-stop action, ADHD-inducing special effects, or jokey cultural references, then this is not the movie for you. If you or your kids prefer a strong story, memorable characters, interesting camera work, a real world setting made magical, and a a dash of that old-time Disney feature feeling, your family will probably like this movie. I wouldn't drag a 3 year old to it, but some 4 year olds and most older kids will find things in the movie to enjoy.
My six year old son enjoyed it in his own way. My wife and I knew the movie would appeal to us -- we've been to Paris and enjoy French cooking. My son -- a notoriously picky eater -- said the movie made him "hungry" and that he now wanted to try a strawberry and some cheese together (like Remy does in the movie). We will see it again, and the DVD will be a definite buy. IMHO, it's an instant classic, on the level with older Disney films that relied on strong stories and vividly drawn characters (such as Lady and the Tramp and Pinocchio).