Little Green Footballs showed the design of the AZ 9/11 memorial. He points out that it bears a striking resemblance to a crescent. You decide.
I do understand that many architects want to incorporate "flow" into a memorial. Certainly, a circle is conducive to that effect. But, why the assymetrical rendering that so resembles a crescent? Given the nature of the attacks, it would seem sensitive to avoid any similiarity.