Decent acting from the supporting cast, an interesting story that is thankfully absent any clichés, and a lack of any "gotcha" in the story certainly help this movie stand out. But really it's the pacing that made it for me. Things happen FAST. They happen logically, and reasonably (well, reasonably given the nature of the story) but they happen quickly. The movie does not have any periods of introspection for our main characters. It suggests that they are having those moments, but doesn't linger on them or play them up at all; they are just facts, like everything else that happens in the movie (fights, deaths, kidnappings, etc.).
The story is complicated, involving at least 5 separately motivated factions, but at no time was it confusing (so there was no need for an "aha!" moment).
The fight scenes were all exceedingly well choreographed and fit the story so well that there was never a time when 2 people were facing off just so we could see them fight; I really appreciated that.
All in all, a very satisfying film: lots of action, lots of very good acting, and lots of attention to detail (it really looked like it was the early 1980s).
I was going to give this a 7/10, but as I was writing and thinking about it, I upped it to 8/10.
