I have no problem with Batman
Spoiler:
killing. DC is really pushing this as an Elseworlds (anyone remember those?) story rather than a more direct translation of the current comics, and this IS heavily influenced by Frank Miller's work, and that Batman was a mean old son of a *****.And besides, outside of his vehicles, I can count on one hand the amount of people Batman kills (future doesn't count, obviously). He goes out of his way to try to disable the guns of the guys guarding Martha. When he stabs the guy, it honestly looked to me like he'd gone for the shoulder to match the wound he had.
Sure, some of his h2h attacks looked particularly brutal, but they do in the comics too. We're talking about a guy that regularly throws sharpened boomerangs at people and "knocks them out". There's an inherent suspension of belief that comes with the character.
He's not the Punisher, even if he's a bit trigger happy in his batmobile and batwing.
As far as the performance goes? Affleck is the first on-screen Batman I've ever seen that comes close to being what Reeve was. One minute he's laid back as Bruce Wayne. He has an almost constant smirk, and genuinely appears to be a playboy. With a simply shift in expression, Affleck drops the mask and IS Batman.
There were genuine times in the movie when I felt it was fading and Affleck grabbed it by the scruff and went "No, you're going to give me entertainment if I have to beat it out of you".