The last installment in the Infernal Affairs trilogy is surprisingly slow moving, but still has the high production values and intricate story of the first two, although as a whole it is slightly less engaging than the preceding films. There have been a lot of comparisons between this trilogy and The Godfather films, and the similarities in story-telling structure and the overall arc of the sequels are definitely there, although I have to admit that I think the Godfathers exist on an entirely different level as these films. The Infernal Affairs films are good, but they're not THAT good.
There is a lot of work in bringing together the stories of the first two films and it definitely adds to them, but I found this one to be too slow moving, although the pace picked up by the third act and the final scene is definitely impressive.
On the other hand, the trilogy ends on a serious downer - "Ksitigarbha Sutra - 'People of the like shall be cast into the Avinci Hell and will continue to suffer from Kalpas to Kalpas with no means of escape.'
I may as well just admit that I don't know the meaning or source of this quote, but it sure seems like a depressing note to end the trilogy on. Nevertheless, despite being just a little bit of a let-down (like countless trilogy finales), Internal Affairs 3 is a necessary closure, and Asian cinema fans are sure to eat it up.