This was an interesting film. While I expected some of the twists throughout the film, others came as a surprise, which is a positive thing.
The shift in the film that occurs a little over halfway into the movie was a unique one, and changes the dynamics of the movie and the characters. Hell, for the most part, I even liked the ending. It's not perfect, of course. I thought portions were extremely unrealistic, especially toward the end, and I have doubts about the "solution" to the problem, as it was. I have to admit also, as much as I thought the main twist was interesting, I lost interest a bit, as the rest of the movie seemed to fall into a suspected mold.
All-in-all, though, the positives outweigh the benefits. The problem is, while it's a technically fine film, and I had little qualms with it aside from what's been mentioned, the movie didn't do a lot for me. It's reminiscent of Green Room, actually - I liked the movie, but beyond a slightly positive outlook, it didn't stand out. While Pet's plot is a memorable one, I find myself feeling lukewarm toward it. It's not that it's a bad movie, it just didn't do much for me. Because of that, I'll rate it around average, though to others, I'd suspect a warmer reception to it.