I have no major complaints about USB3.0 (native or not).
AMD northbridges have some PCIe 2.0 lanes to spare. And even if the NEC controller was connected to a PCIe 1.0 lane, it would still be much much faster than USB 2.0.
AMD made the right decision to prioritize native SATA 6Gbps (which is kinda pointless now, but we'll have 6Gbps SSDs very soon).
I just wish they had both...