I saw Zodiac last night, and it reminded me of Breach in a different genre, the serial-killer thriller rather than the spy movie. Both movies are based on actual cases, and it seems as though both deliberately deglamorize them. In Breach the spy has been uncovered long before the beginning of the movie, and what we see is just the conclusion of the case; in Zodiac the killer isn't the clever fiend of Seven and a bunch of other movies I haven't seen; he taunts the authorities, but his ciphers aren't that hard to solve and don't always signify that much, it's not a procession through the Deadly Sins or the signs of the zodiac. Due process and procedural issues are prominent in both films.
And both movies seemed to, or seemed to aspire to, be liberated by being forced to follow an actual case. The facts of the cases didn't fit into the conventions of the genre -- so the movies had to do something else than follow those conventions. Now those conventions exist for a reason, and the movies might have thus lost satisfying resolutions and the Aristotelian unities; but they were also forced to try to do something else. Contrast The Good Shepherd, which was loosely based on facts but which also had a conventional find-the-leak plot as an important element -- see here for a spoilery critique, which is harsher than my own view. If the movies want to say something about how being a spy/detective/obsessed journalist affects your personal life, it may be sometimes more effective when it's not being hung on a genre plot. (Or not, I'm sure there are counterexamples.) Zodiac was more effective than Breach in this way, because there were more and more interesting personal lives.
Both movies also generated some effective suspense, which felt a little more earned for being less contrived (though that just means: a more effective contrivance). There's one particularly funny suspense scene in Zodiac that benefits from this effect; it's a hoary old trope of this kind of movie, but given that the story actually has to follow the facts you don't know what's going to happen in the movie. (Except I'll bet that even if there was an incident somewhat like the one I'm thinking of, it didn't happen nearly the way it was described.)
At the movie theater there were incredibly long lines to see Wild Hogs.