I didn't like Act III either. Compared to how much I loved Act II, it was quite disappointing.

I didn't mind that they killed a major character (I had actually expected Billy to die), or that it ended on a morbid note... I was fine with the conclusion that the world sucks and the villainy has been achieved. I was just disappointed with HOW they got to that conclusion. It was mundane, it was predictable, and I can think of about seven or eight ways already to reach the same conclusions but in a much more wacky or creative way. And it didn't really end so much as...trickle out.