Rocksteady's new and final Batman game has now been delayed to 2015, unfortunately. No official reason has been announced, but it's fair to assume, since the game is on such a massive scale (or at least it looks that way from the trailers) that they're working hard to patch things up and fix bugs and glitches and make the ultimate Batman experience it promises more enjoyable. No official release date has been announced either.
It is fair to be disappointed, as I don't think any company should release an official release date unless they're completely 100% positive, but if it's to make the experience better (and not pushed back an entire year; hopefully it comes out beginning of 2015, summer at the latest) I think it will be more than worth the wait.
And if you're really disappointed, Lego Batman 3 comes out this fall, so I hope that will be enough to tie you over.