When Batman was flying off with the bomb, I kinda rolled my eyes with the "hero sacrifices himself" ending. I bought into it. It sucked. Alfred crying... very moving. It was predictable, but I could respect it. Sucks to go out on a low note, but sometimes that's the best way to tell a story. And then they turn it around and reveal it was all fake. Instead of feeling elation the hero survived, I felt like "you bastards... you put me through all of that just to wimp out?" On top of that, Batman quits? To live the good life in paradise with Catwoman? No more duty to his city? (granted they did turn out to be a bunch of ungrateful, cowardly, murderous thugs...) He just abandons his life's mission? Retires? Really pissed me off.
The "Robin" reveal... not horrible... just lame. And he's going to become Robin without Batman? Guess they had to hang a sequel onto something...
Good points on the timing, and I didn't think about the devolution into anarchy of Gothamites being so different from the way they acted in TDK...
But regarding the ending, I took it less as Batman's retirement and more as maybe a little vacation. Robin's going to get **** in the Batcave all cleaned up, and in a couple month's Batman will be back. Something like that makes it a little more palatable.
I knew the Miranda chick would turn out to be Talia for some reason (mostly all the pro-environmental crap she talked about in the early scenes), though I didn't see her being quite the full on villain the way she was.