It was very good, but the ending left me unfulfilled

Rating: 1/10 (8 October 2006)

Coming in to "The Departed", I was lucky to already know what the plot was about (some trailers are so obscure as to not mention jack-crap about the plot, to hide the fact that it sucks) and it got four stars (highest rating) in my local newspaper's movie reviews, with lots of great mention on acting and drama and directing.
The movie was very well-done. It was a bit confusing in the start as some of the actors mumbled and made it hard to understand them, but this didn't deter from the plot as though you missed something important. The directing style wasn't too special at first, but showed some definite high points and strengths later on (the scene where Martin Sheen's character, chief Queenan, is thrown from the roof of a building in slow motion, a bunch of people in the theater I was in gasped audibly, and even more so when he hit the ground)
The acting of Leonardo DiCaprio and Matt Damon, not just in the movie, but in their roles as rats, were very convincing (some scenes with DiCaprio, and Frank Costello suspecting him as the rat, made me genuinely think he wasn't a rat, but rather pretending to be one.)
The dialog is crisp and never seems to falter with uselessness or insanity or something off the wall completely. My only complaints were that Matt Damon's character Colin Sullivan had some unexplained obsession with the golden dome roof of a church, in which he'd constantly stare at in his apartment. This was never explained or even delved into in the least. Another was the mild hint at Costello slowly going crazy over the course of the movie. I didn't see this at all. He did some eccentric things in the later course, but nothing to truly qualify as ascending derangement.
The movie peaked when the two rats discovered each other out (after Costello's death) and DiCaprio's character William Costigan went out trying to expose him, even going so far as to lure him into a trap and trying to arrest him, despite not being a cop (his identity was erased for secrecy reasons during his mission, which only the police chief who was killed knew, and the Sergeant played by Mark Wahlberg, Seargent Dignam, who left the police force rather than hand over the identity of their rat in Costello's group).
It all seemed to go downhill from here as Billy Costigan is killed by an officer who was revealed to be a second rat working for Costello, who then let Sullivan go. He then killed one of the officers who was friends with DiCaprio's character, and then was killed by Sullivan. Then he went home, to discover Dignam there, who then killed him and wandered off.
The final scene is that of Sullivan's balcony, with a view of the golden dome church, and a rat on the banister sniffing something. For some reason, this ending left me unfulfilled, and a bit disappointing, almost anti-climactic for a movie which was building up so much intensity, complexity, and drama.