I would consider the lack of TB peripherals a big disadvantage to USB3. Then when they do come out the cost will be another big disadvantage to USB3. I keep saying it and will get all negative votes from fangirls but in its present form with the lack of anything to take advantage of TB's speed, its just another firewire. By the time firewire drives came down in cost it already lost the war to USB, which is really too bad.
I've read through a lot of these threads on MR since TB was announced, and I could probably find 1 in 10 forum members that conceptually understand TB.
TB is fast now and will be faster still in the future, but it isn't just about data transfer. It's about latency, in the neighborhood of 8 ns, synchronization of data streams, and flexible protocols. These are not strengths of USB 3.0.
Apple, Asus, Acer, and Sony see a future of mobile devices morphing into full fledged workstations, and if that is what is desired, TB has the underlying technology that USB 3.0 does not.
Complementary is how Intel would describe TB an USB 3.0 and I would agree with that.