I just got back from seeing this. I have to say that for most of the film I was on the edge of my seat.. I'd say that this was largely due to the incredibly powerful and original film score (sooo powerful throughout).. but got a little bit lost towards the end?
I felt complete sympathy with Daniel Day Lewis' character, throughout his moments of meglomania and suffering... (yes, a bit odd, I know, and I wonder if anyone else actually felt this) and actually really liked him as a character.. up until the final few scenes where it really just became apparent that the man was insane.
A bit disappointing that there were so many unanswered questions... but hell, what a film score!