Maybe I'm just pairing the two movies because they're both undersea adventures, but I couldn't help but notice how it copies Nemo in a few ways.
Anyway, the movie was enjoyable enough and doesn't deserve the hate it's receiving from some. Although, they were some odd elements that I'm not sure were entirely appropriate for children, namely the blunt discussion of reproduction/mating to repopulate the oceans, as well as the sheer amount of fish & human skeletons throughout. Now, it should be clear that these were just cartoonish skulls and bones and wouldn't go as far as to traumatize any children, but it was still a little morbid. Speaking of morbid, the bigger picture, outside of our fish's adventure, is that the world is in such a sorry state that humans have long left the planet itself... I mean, that's not Walking Dead level of dystopia, but it's still a little bleak for a children's movie, no? All of this wouldn't stop me from letting a child watch, but it is a little odd.
Other than that, the animation was top notch and looked pretty cool. Each character is pretty one-dimensional, but there's enough characters and creatures to give the movie the variety it needs, ranging from shrimp to whales and all in between. A visually appealing movie, no doubt.
A lot of people have been ripping into this one for not being entirely scientifically sound. This is a movie where a penguin pilots a spaceship, get a grip. This isn't one of those Pixar masterpieces that is enjoyed by parent and child alike. It's a silly kid's movies, and it serves its purpose as that. Saying that, it wasn't outstanding or anything. Funny at points, and creative sometimes too, but Deep is nothing too special.