I used this flash professionally for a couple of years shooting weddings and portraits - quick cycling so it's ready to shoot again shortly after firing (especially with a Quantum battery pack), works great with a Canon 5D and the 5D mk 2, eTTL II was mostly ok and it's got plenty of range for most situations.

I'm not sure how many jobs I used this for and it only started showing it's limitations when I got into using off camera flash - the lack of a PC socket means a remote radio trigger like a Pocket Wizard can only be used with an auxillary hotshoe adapter which while possible, can be a bit fiddly, especially if you're working in a hurry.

In the end I upgraded to the 580 EX II precisely because it had a PC socket (and the extra features and weather proofing are obvious bonuses too), but I keep the 430 and use an extension cable to hand-hold it off camera. A great flash, and the limitations won't matter to most people.