I'm giving this 5 balls of yarn, even though I got some knitting done and The Batman's voice drove me crazy. This is a superbly acted and beautifully shot movie. It's dark, and when people say that, they aren't kidding!
Forget the fact that they are marketing toys to small children: parents, this is not for 8-year-olds! Most of the violence is cartoony enough, but there is one part where a villain holds a gun to a child's head. There's more info. here. It's rated PG-13, and I wouldn't take a child much younger than that (maybe a mature 11 or 12). Best bet: preview it yourself first.