I was expecting Sea Level to be a cheap Finding Nemo ripoff similar to those bootleg Video Brinquedo movies, but it has a lot more effort put into it than those. The movie does have some interesting ideas, at least, but it's EXTREMELY slow. I almost fell asleep multiple times watching this, it's a huge slog up until the last 20 minutes or so.
The best parts of this movie are the action sequences, they're actually pretty engaging and fun to watch. There are a lot of them towards the end of the movie, but for the first ~70% of it, you'll mostly just be watching the characters talk. This would not be an issue, except this movie's dialogue is just so BORING. I don't think there was a single joke or witty line in the entire movie aside from a few sight gags. In addition, the movie's voice acting is...not great. The voices of the humans are all terrible, and the voice of Pup (the main character) gets pretty grating after a while...he just sounds really whiny the whole time.
I also don't think this is a very good movie for children; this is partially because the movie is extremely boring and won't retain their interest for very long, but also because a lot of it is just...not really appropriate to be showing to young kids. Mind you, I don't like it when parents go over the top with sheltering their children, but this movie is a bit more...extreme than most other children's animated movies I've seen. There's blood, animal carcasses, a physically and verbally abusive family, and at one point one of the characters says "hell". I wouldn't call my parents overprotective, but I doubt even they wouldn't have let me watch this movie.
All of those problems aside, the movie does have some good parts. I liked how the water and land animals kind of came together at the end, that was a neat idea. Making the main character a mudskipper (a fish that can breathe and walk above water) was also a cool concept, and it becomes very important later on in the movie. The other characters weren't much to write home about, though, aside from the chickens. The chickens were a lot of fun. Aside from them, the rest of the ensemble cast is pretty lame, and there's a "villain" (the eel) that literally does nothing in the entire movie. You could take him out of the movie completely and nothing would change. Also, like I said before, the action sequences were entertaining.
Overall, while Sea Level is WAAAY better than I expected, it is not a good movie. Watch Finding Nemo or even Shark Tale instead of this.