Customers most agreed on the following attributes:
I bought this to use my Canon Speedlite 420EX with a recently purchased Mamiya RB67. Works very well. It's quite reliable although I had a problem once where the PC cord did not make good contact with the socket on the lens. I give it four stars, because it is a bit weak (i.e. the plastic mount kind of bends in a metal hot shoe).
Overall I think this is a good product. The construction is not the best, but its solidly built. I have had a couple issues with the pc cord staying in the socket on my camera but it stays in the socket of a radio flash transmitter fine.
I use this with an Minolta 320X flash for wireless shooting. I find it to be more reliable than using the hot shoe on the bottom of the flash. I know I'm not going to have a misfiring problem this way. The reason I gave this four out of five is because I do not like the feel of it. It's rather light weight and feels kind of cheap. I'm afraid to have the flash pointed a certain way cause I feel like the flash will fall out. So far it hasn't but the fear keeps me worried.
It works. I needed one for an older camera w/ PC Connector - and it works. Very flimsy, however, I can tell it won't last unless you're very careful w/ it.
It does exactly what i need... having 2 flash units operated by the camera directly.