while I liked the movie.
I had some problems with it.
spoiler*****************
I knew that when it came to the container truck scene with the shoot out with Costello and the police that the ending was going to be a far cry from the greatness of the movie thus far.
my problems with the ending were this.
There are many things Costigan could have done rather than confronting Sullivan on the roof of that building.
He could have gone to baldwin with the same very recordings that he got from Costello's lawyer... which would show that Sullivan was the mole in the department... record of him being police or not... it would explain how his record was deleted etc..
he could have found Digmann where ever he was and gave him the recordings and Digman would come forward and clear Costigan and arrest Sullivan.
So for all those people to cry plot holes, cry foul at this, why would he do it that way... if you say it is because he wanted to die, then fine, but i dont think he had a desire to die there in that elevator.
its just an excuse by the director to kill the main protaganist at the end, because people believe its more dramatic than flying off into the sunset...some times it is , some times it isnt, in this case it wasn't