^ In terms of rate stats, Kevin Martin averages more assists / has a higher assist percentage than Harden, and has a lower turnover percentage as well. Rebounding has been about equal, and both have been fairly efficient. Martin, of course, is a substanially more prolific scorer.
I'd give Harden the edge in defense, health, toughness, and upside. I think he will be better than Martin, but I don't think he's there yet.