I am a little surprised that so many people were not able to get their hands on this unit. They have been available at numerous authorized dealers at similar or even lower prices compared to BHphoto since launch.
Those thinking about making the jump to radio should do it. It is awesome not having to worry about LoS and the all-in-one package of the 600EX-RT is both more compact, less expensive (vs. 580EX II + PW) and more reliable than other wireless solutions. Huge downside is that it is quite expensive to upgrade exisiting gear. I am optimistic though that a third party manufacturer will make adapters compatible with Canon's RT system so that you can used any flash (Canon, Yongnuo, Bowers, ect) with the system.