I don't like Froch, he's a twat, but I find him amusing and like to watch him fight. I don't know much about Kessler except a lot of people on this board who I respect their opinion seem to rate him highly.
IMO Froch is not world class, he was being soundly outboxed by Brian Magee who's a european level fighter at best, and only got past him because Magee's chinny and a light puncher.
Froch does have some qualities, he has decent power and is always in good shape, and has some guts as well, but if Kessler is as good as some people claim he is, Froch doesn't stand a chance