Well, due to all the hype I went to see this one with great expectations, although I must admit without having seen the parent film Infernal Affairs. What a let down ! Setting the scene is great, and time taken to achieve this is well spent, but for me the film started to drag, with expectation and patience well run out by the time the plot strands began coming together. Yes, Jack Nicholson is a great actor, but no he didn't convince me in the role, even though most of the good lines and deliveries were his. But Boston Irish ? Everyone, including the deliverer of the line "I'm Irish & can live with something wrong the rest of my life...." failed to convince me of Irish lineage. The accents, the faces, the attitudes were all wrong for souls in torment over doing what they believe they have to do, a basic for Irish/Catholic guilt and angst. <br /><br />The film would have been much stronger with unknowns in several key positions, and for me once the disparate strands were established the rest of the film was very predictable and I wasn't kept guessing - crucial if we are to suspend disbelief and have pressure and tension build in the viewer.<br /><br />DeCaprio fails to convince as a tough guy, despite the convincing scars. He stills comes across as an adolescent fuming after his pocket money's been withheld. Matt Damon looks like an awkward schoolboy, and was even less convincing than DeCaprio about being a cop. Mark Wahlberg sounded like he'd been taught to swear the week before, Martin Sheen was as hard bitten as a kitten and there were so many operational goofs the film became a comedy. A Federal agent running a State operation against his own informer? What a waste of time and budget monies. Only two people knowing about an undercover operation? BULL! Keep sending an undercover back after his nerve's gone ? Garbage ! Permanently deleting a full record (on a State Police computer no less!) without possibility of recovery ? Unbelievable - even children know data can be restored, and the system will keep a record of who deleted the information. For me, the film became a joke and I couldn't wait for the end to arrive so I could leave. By the time the end plays arrived and new players were falling like flies, the audience was laughing out loud at the inanity. Once again, Hollywood takes a good story and ruins it with poor crafting, no matter how well filmed. Very bad casting, a rushed and unfulfilling ending, far too much gore, not enough character substance, one dimensional players and an insult to the viewers intelligence.