Ah DVD commentaries. At best they can be thoroughly informant and entertaining. At worst they can be very tedious, going-through-the-motions chat that make you want to switch the audio track back to the film. When I'm watching DVD extras, I'll always leave the commentary to last just in case it's awful and puts me off the rest of the supplemental stuff. But sometimes they can be great - the first one that comes to mind is the one on the Green Mile special edition.
Superman doesn't care about humanity. The bad guy wants to save the world. Batman can't get it up.