I've been using them for a few months now and they are very easy to use. Once I found out how to set up on camera TTL and off camera manual, that is (thanks Miguel)
Ok now for the next step. Don't you guys think it's time the Canon & Nikon engineers give us what we really need, fully integrated, TTL, remotely managed, radio controlled studio lights? How sweet would it be for Canon to scale this flash head up to something like a Quantum, Einstein, or even greater power level? I would pay $1000+ each and buy a complete set! Well actually, I'd pay for the Nikon version. The camera makers are missing out on an easy and lucrative horizontal integration opportunity here.
How are people finding these with a 5D II ? As have the 5D two an three , just don't want to expect too much inconsistency when shooting with Both bodies. As I plan to get 1 x st-e3 and 2x 600ex.