I'm normally a fan of English gangster movies. Their grittiness and wit usually entertain me. This one, sadly, did not. It isn't really a gangster movie as much as it is a morality play about catharsis and existentialism. Because of that, there is no real story or plot and it doesn't get going at all. It would be better suited for stage rather than screen. I spent most of my time feeling like I was watching the retirement home for Guy Ritchie characters.
However, for what it is, it is done very well. The acting all around is very good, especially from Ian McShane. That is saying something because I am not an Ian McShane fan. It is also very well shot and the lighting is perfect to set the mood. However, I did find that it felt like a BBC drama at times rather than a film. Also, it was difficult at first to tell the difference between real time and the flashbacks/Colin's mind scenes. They should have been shot differently. Otherwise they get a bit confused.
The bottom line for me is that you probably shouldn't see it. But if it can be seen on the stage, it might be better.