I can't emphasize enough how accurate [MENTION=7585]Kean[/MENTION]'s comment on the previous page was, about Batman needing a dynamite script to be effective. Christopher Nolan nailed Batman, and Christian Bale was the perfect choice to play him. You can have the greatest actor in the world play Batman, but if the script isn't there MAKING him cool, it won't work.
As an avid Batman reader, I'm always leery whenever a new writer takes over the Batman comics or a new project is initiated on the big or small screen, simply because as a huge fan of Bruce Wayne, the writer/producer really needs to get Batman. They need to understand his unique presence, what makes him cool and especially, what makes him special without superpowers in a world with superpowers. In a team-up movie like "Batman/Superman" or "Justice League", that's even more important.
For the upcoming movie, I think it's important that the idea gets transmitted by the end that Batman and Superman are friends. That the entire DC Universe looks up to them, and that that singularity of focus and command if you will, weighs on them. As such, they really, truly understand one another, even when they don't agree, and they are the only really, true "friends" each other has. The comics, especially the relaunched Justice League title under Geoff Johns, GETS that. Clark Kent is the only person in the whole world Bruce Wayne really considers a friend. It's something that makes their relationship and friendship very unique and very cool.
I think Affleck can work well. If I knew nothing about him at least, I would look at him and say "this guy really LOOKS like Batman". I think he very much has the physical presence to pull it off. At the same time, before he was even cast, I knew that nobody could ever replace Bale for me. To me, Christian Bale is and always will be THE Batman. I accept that and I love Batman, so I'm willing to give the reboot a chance. I'm not expecting Affleck or the movie to exceed or "beat" the Nolan/Bale trilogy. It's its own thing, and I think Ben Affleck can do very well with it.