The movie presents an incredible introduction that shows you the acting ability of its main character and the intelligent direction style.
The first big problem is that we are never really able to empathize with the pig character, cause the protagonist's life becomes positive from a scene to the next one, depriving us of seeing how the character evolves or how the pig is affecting her life.
We see that it does, but not how, so, it never becomes a lovable or a trascendental character.
In not doing so, we never really care about what happens. Yeah, at some point it is irrelevant, 'cause the important thing is to see how that relationship affects the main character, more than the audience, but at not doing that, we never understand the feelings of the lady either.
I think the biggest mistake is in the third act, 'cause at a certain point the plot gets lost and never moves; we don't see a real conclusion, or the resolution of any conflict.
Anyway, Cría Puercos is a movie that stars on the right foot; and the good direction, the well-constructed dialogues and the acting ability of the main character keeps you interested of what is going to happen (even if it never really happen).