There is so much animation coming out of late that it's getting hard to really peg a film ... but this one seemed to be heavily focused on translating the facial features/gestures of the voice talent into their animated characters ... I suppose that if one is paying for a lot of "big names" that you want to point it out (sort of the opposite of the Garfield movie where Bill Murray was totally wasted as Garfield's voice), but there wasn't much "what can this star bring to this character?" (think Mike Meyers fleshing out Shrek) and more "gee, that's what Will Smith looks like as a fish!". This made for difficulties when you didn't know the actor involved ... for instance, I don't think I've ever seen anything with Renée Zellweger in it, so I was having a hard time figuring out who the fish character Angie "was" among the more familiar faces (voices). To go back to the Shrek comparison, Princess Fiona is a role that Cameron Diaz acts, not just an animated version of her ... almost every character in Shark Tale is a caricature of the actor voicing the character, and not a character developed by the actor
That said, it was an amusing movie with several quite endearing bits ... but it's no Shrek ... heck, it's not even a Treasure Planet, but it's not a bad film.