I was frankly disapointed, but in retrospect, I think the problem with this movie was the marketing.
See, it was a fine little movie. It wasn't complicated, it wasn't dramatic, it was just a mild little tale of magic fish. As such, it was enjoyable and there were bony fish, which were kinda neat. I'd put it somewhere in the range of Kiki's Delivery Service, (alas, without the cat) just under Castle in the Air, but a fun little film.
The problem was that the marketing I heard included overblown phrases like "What Miyazaki attempted in Spirited Away and Mononoke, he achieved in Ponyu!"
It wasn't the same sort of film. It was a nice little movie, but Spirited Away was bloody EPIC. I mean, if I got one movie on a desert island, it'd be Spirited Away. And I can't watch Princess Mononoke without bawling for the poor boar god.
Now, look. I , of all people, respect the right of artists to do some things that are small and gentle and whimsical and not BLOODY COMPLEX EPICS. God, do I understand! I do Digger, which is the stupidly multi-volume epic, and then I draw hamsters, or do the short and sweet "Little Creature" or whatever. And I am not in Miyazaki's league at all, but I think the principle holds--there are a lot of stories, and the vast doorstop ten-book epics are not the only ones worth telling. You tell me "This is a quick and silly little piece," and I respect absolutely that's what it is, and I'll enjoy it thoroughly on that level.
This was not a movie of epic spectacle. And that's fine, not everything needs to be. Had I gone in expecting a nice little film with maybe some Devonian bony fish, I would not have been disappointed, but all the hype was screaming "MIYAZAKI - MOST EPIC WORK OF MOST EPIC GENIUS OF OUR TIME!!!!!" and...well...it wasn't.
So, go see it, even a small Miyazaki movie's worth seeing, but don't believe that it's going to put Spirited Away in the shade.