No spoilers here, though I'm aching to spill 'em; I'll just say that the ending was fantastic. In fact, I think I liked it even more because I'd read online somebody complaining that the ending was sudden/just a setup for a sequel, etc., so I was expecting at any moment the game to suddenly just stop and roll the credits. And when it in fact didn't, and instead pulled so many elements together in a thoroughly satisfying way, I was cheering. So thanks, crazy wrong Internet person! You made me enjoy this game even more.
Also there's a pretty cool song over the closing credits ("M4 Part 2 by Founts," according to my hastily scrawled note.) I'll have to track me down an MP3.