Notice that almost no one gives this film its average score (around 2.3 stars)? It's a classic bimodal distribution: hate it or love it. Well, maybe "love it" is a bit strong, but for those who 1) don't know the plot ahead of time, and 2) carefully follow the plot as it develops in the film, particularly in the last quarter, the story is quite gripping. If you've read the story ahead of time, or lose the plot while watching, it will just seem like a very low-budget muddle.
Like many of Gibson's stories, this is hardly science fiction-- in fact, it's more purely noir than many other more noir-y looking films that come to mind. As such, it's about money, love, betrayal, women, memory, machismo--that sort of stuff. Having read the story after seeing the film, I'd almost say the movie was better, while still being true to Gibson's spirit: less of the narrator's whiny voice, more Fox; more mystery, less pseudo-futuristic-cosmopolitanism. And a much better finish.
The best part is really the much-maligned last quarter, which in its memory flashbacks leads you to discover for yourself who betrayed whom and why. The conclusion, if you care about these sorts of issues at all, is really quite sad and moving. Not knowing when it would end, I jumped up close to the TV to hear Argento's reply to Dafoe's last line. To end there shows that these guys knew what they were doing.