Finding Dory shouldn't have worked at all. It's 12 years since the first film, the story robs the original of one it's most subtly complex moments, and there was a distinct whiff of Minionitis about it. But damnit if Pixar haven't done it again.
The film is a richly coloured, complex and emotional joy, which might not break the mould in story terms but manages to trade exceptionally well on all of the things that made the original so popular. It's not quite up to the standards of Toy Story 3, but there's not another Pixar sequel that can outstrip it or its commitment to advancing the story, building on established chemisty and successfully introducing new characters.