I got to give mine a try this weekend, but just for a quick portrait session – my real intent with it is for architectural work where I often have flashes in other rooms or even outside. For portrait/product work it’s probably faster to just adjust power at the flash.
That said, for $50 I’m pretty impressed. My only real complaint is that the up/down buttons only do the 1/3 stop increments, I wish I could use them to quickly choose groups and have another button combo for fine tuning. Lack of AF doesn’t really bother me, as I use manual focus for my architectural work and my 6D usually finds focus regardless of the lighting. But everyone has their own uses and work flow. Seems like it wouldn’t have been hard to put AF in, but what do I know.
I’m sure I’ll end up buying another 560 III or two just for convenience, although I have no need for more flashes. It would have been nice to have them function in groups with the 602/603, but I’m sure the technology just wasn’t there (unless you used channels). For my work I can’t really see using more than 3 groups, and it’s not usually the absolute power of the lights as it is the ratio relative to the others. So 2 or 3 controllable lights should be sufficient, and the others can just be dummies.