I was one of the most critcal on affleck as Batman, but after the past trailers i feel that he will actually do a decent job as bats!
I actually think he will be pretty good.
It's all about the writing and the story.
If the story is shit, no actor can save it (Daredevil and Gigli to keep it Affleck related), but if the story is solid, then it's just doing what the writers and directors want you to do.
Affleck may be a better actor now that he's been on the other side of the camera as well. He may understand more about whatever "vision" a good director has for a movie.
The trailers make it look very compelling... I will definitely go see it.