So far, pretty damn good. The only negatives are no Bill Ward (although Wilk is servicable) and Rick Rubin's overly loud, distorted production that he screwed up Metallica's Death Magnetic with. Unfortunately the public doesn't seem to care about bad audio quality, so it keeps happening.
Regardless, Iommi is kicking out the killer riffs showing that without him losing the tips of his fingers, metal as we know it would never have existed! Ozzy's voice pairs perfectly with Iommi's riffs, I never felt Dio nor Gillian's did although they're great singers it was just the wrong style for Sabbath.
Songs are catchy, headbang worthy and awesome so far. I'm glad it didn't end up a disaster of a band trying to recapture it's glory days and falling flat.