So bizarre it's charming
This is a "so bad it's good" movie for adults, and might keep kids entertained simply because things are always happening.
At its core, it takes the Noah story and somewhat shoves Noah aside with talking anthropomorphic animals to focus on the story of a young, vain, and horny king lion learning to become a real leader with the help of a smart replacement love interest. It almost works, but the human parts tend to fall flat and the animal parts tend to go to extreme tangents a bit long.
As well, don't be fooled into thinking it's very religious, it's more akin to Ice Age with a bit of God on the side to drive the plot.
I must note this review is for the uncut version, not the later cut version available on DVD. The main difference is the inclusion of some more sexual parts, and I think it's actually better with them, as without it would be quite boring, if more appropriate for younger children.
Certain parts are rather sexual and the humor is crass.
At one point, the king lion and his original lover are heavily implied to be having sex based on a character's reaction and the way they're seen after a cut to them. There's a few instances of very shapely anthropomorphic females dancing suggestive as well.
There's a lot of toilet and butt humor, including several instances of small animals going up the butts of larger ones, to the point that a character even dies presumably either from being up one, or from drowning.
Similarly, on grossouts, there's a bit where some characters end up in a pile of rotting garbage (and presumably poop) that is disturbingly better animated than everything else.