Sadly, it's not very good.
The concept is pretty funny. The sincerity in which the characters behave adds to the ridiculousness of the plot. But there's a shockingly small amount of humor. I appreciate subtle comedy, but it's nearly non-existent here. There is a funny moment where a character freaks out about getting ranch dressing on his pants, but that's about it.
It doesn't help that the two main guys are dull and unlikeable. I wanted to root for the main guy, cuz I'd totally wanna react the same way if anyone hurt my pets, but I ended up thinking he and his cousin were just a-holes. But their real problem is they just recent interesting enough to make me care.
Finally, and worst of all, the film completely wastes Kristen Wiig. I'm all for seeing her in different kind of roles, but different here doesn't mean better.
I feel like I'm being harsh, but I feel that it would be unfair to make excuses for the film just because of the goodwill I had built up toward it. I wish I liked it more than I I did. That's probably the best thing I can say.