Both Robert Downey Jr. and Val Kilmer excell in their respective roles, and I'd be lying if I said the snarky banter and ocasinal subversive gags weren't fun to watch. However apart from that, there's very little about Kiss Kiss Bang Bang to recommend. The plot is both uninteresting and nigh-incomprehensible (although one might argue that's par the course for noir detective fiction), the fourth-wall-breaking jokes generally come across as annoyingly self-satisfied, the pacing feels very off and there's very little sense of narrative purpose to anything, and its constant shifts between grittiness and goofiness are jarring, to say the least, and sabatoge the film as both a comedy and a thriller.
Cut up into individual unrelated scenes, the movie would work. But as a whole it really doesn't. Much like Kingsman: The Secret Service, its satire and subversion don't really excuse its lack of originality or its uncomfortable tonal inconsistency. It left me with a few quotable lines, a reinforced respect for Downey's abilities, and absolutely no other impression one way or the other. Would I see it again? Probably. Because after a few months I'll have forgotten everything about it. Apat from "look up idiot in the dictionary."