There is one scene that makes the whole movie worthwhile, when they say goodbye. It has such an Asian feel to it: it's all heartbreaking but inevitable.
Other than that, it goes from weird kung-fu action against cuddly 3D animated monsters to fart jokes, birth jokes, marriage jokes and family problems, then back again so fast that you don't really know what you're supposed to be watching. And occasionally they just randomly start singing, fortunately not too often.
The story follows a hapless young man and a young female "monster hunter" in the context of a monster hunt. On orders from a very powerful man, all hunters are on the lookout for the monster queen and then her infant offspring. These are all very powerful kung-fu masters, but somehow they get thwarted by the power of youth and love and after much adventure and a twist, a happy ending.
My conclusion is that this film combines a lot of classic Chinese concepts: the humor, the fighting style, the overlaying culture of it all. My guess is that it was aimed at young Asian children and, while it will probably be enjoyed by children everywhere, Western adults might find it crass and infantile.