3. The part where his daughter kills him and it turns out to only be a dream was a complete cop out of an ending. The movie did something really cool and then it took it away like a sneak thief in the night!
On one hand, yes, it does seem like a "cop out"...
...But, on the flip side, there's at least some sort of reason for such a "cop out" -- unlike most movies where they do a "cop out" to give no reason story-wise for it but to do it basically to just facilitate plans for a possible sequel.
I thought the ending of him dreaming his daughter killed him proved exactly to me why he decided to kill Dane Cook, in the first place -- that Mr. Brooks was going to stay alive to try and stop his daughter from getting worse and turning into the serial killer that he has already become; or maybe stop her from possibly becoming even worse than him.
Or maybe he'd fail in such an attempt, like his dream showed could happen...