I thought the script relied a little bit more on gimmicks and had a shade more preposterousness than other Pixar flicks, but of course when you're talking about dogs flying airplanes, and a lost land in South America, and floating a house around by having it tied (with string) to a bunch of balloons you're already well into the land of speculative. Some of the stunts were a little hard to believe, but again, it's a freaking floating house!
Another strength of Pixar's storytelling is how there are little things in the plot that come back later or explain things without having to explain them. Examples here are: "Squirrel!", the tennis balls on the cane, the names of the dogs, the squeaky collar, the helium tanks in the front yard, and the GPS (which was used then conveniently resolved). There's plenty more as well.
Overall, a highly enjoyable movie that I would recommend to all ages. It's the second week but the theatre was packed with families, which is a good sign that the movie will have some serious legs and keep Pixar in the movie-making business for some time to come. Which is a good thing for all concerned!
