First of all, I've never been a fan of Doomsday, but seeing as how Morrison made Egg Fu an interesting character, I think he could do wonders with the one-note Doomsday.
I've always thought a being called Doomsday should be a more metaphysical menace, something that can't be defeated by beating it up. That seems to be where Morrison is going with Superdoom. What if, in fact, Superdoom was what killed Superman in the New 52? (We know he still died, as it was vaguely referenced in Swamp Thing).