I have a very complicated plot. I have a lot of complicated machinations at play, a lot of weird shit that happens, and a lot of characters who know a lot of things.
Everything happens for a reason. It's all very detailed, very planned.
The problem? I hate exposition. I hate writing it, and I hate reading it. It's hard to make everything that gets exposed seem natural, and my characters, with one exception, aren't really the kind of people who would just sit down and tell people what they know. One of them would get impatient and roll her eyes. One of them would lecture the other characters on things that have nothing to do with the situation at hand, but that would impart a lesson that would clue them in as to what was going on with the situation.
So as I reach the end of my book, everything is happening, but why it's happening just isn't being explained. I guess I'll see what people think when I give it to people to read, and see if they think it's a problem-- maybe more is being explained than I think, maybe they'll be able to pinpoint where I need to explain more, whatever. But all the stuff that was supposed to "come out" by the end of the book, well, just isn't. I don't know if that's a bad thing. Maybe it's more natural, but I want to make sure that if I'm leaving questions for the audience, they're questions that will make them want to piece together what happened, and not questions that will make them be like, "uh, WTF, that was stupid."