I actually don't mind graphics taking a hit if it means a bigger city. As long as the framerate doesn't take a major hit, and screen tearing isn't a nightmare, I can be happy with more to explore if the graphics take a dip.
I've enjoyed the Arkham games way too much to pass on this. I feel like if they keep enough of what Rocksteady made work, that I'd be happy with that. If we get a better story or even just a good story out of it with Batman stuff to do, then I'm still in.
I watched a gameplay demo of it, and yeah, it pretty much looks like AC to me for the most part. But, that's pretty much what I was expecting.
Now, if they can give me a Batman Begins skin, I'd be first to declare it GOTY just for that.