This is a much debated topic. Everybody has had different experiences.
Mine:
3 OCF chords that went south almost immediate, one of which came apart the first time I pushed the flash on the end.
7D that did not quit live up to my expectations as flash commander
ST-E2 that actually works better than I expected and also works well for low light AF support.
I would love to try out the 3 party unit, not that I would buy one.
The Radio Popper ETTL unit intrigued me, but I didn't really like the DIY feel to it with the sensor thingies and cost.
I almost considered PW's, but RFI issues with the 580's and cost.