That was my reaction as well; I sense that this clamp would be helpful to align and hold the pieces at 90 degrees, but the pocket hole screws would actually tighten the joint. I have several corner clamps, including four of the type Mark mentioned, but none of them pulls the joint tight without the kind of extra help Mark mentioned. From what I can see online, Woodcraft is the only place that has the Kreg clamp in stock, and I don't have a store nearby. Maybe somebody will be able to give a hands-on review.
Tony