"Sins?" B&R wasn't good (though for the self-mocking romp it is, it isn't horrible either), but Clooney's performance wasn't at all lacking, given the context.
This... I thought Clooney was perfectly cast in the role. The problems with B&R were with over production and Ahhhnold's over the top one liner-based script.. Well and just the awful script in general...
Clooney would be a great choice for an older, gritty Bruce Wayne/Bats, but it would never happen due to the bad taste in everyone's mouth from B&R...