Lots of discussion about these in the trailer forums.
I have one and have no complaints. It seems the older style that bolted onto your existing reciver hitch (insted of a ball) was prone to failures in sudden stops. The hitch would remain intact, but would be destroyed.
The Style I have goes into my reviever. Zero issures with it, much much much better than a ball, and cheaper than some other options, such as MaxCoupler, which seems to be the favorite.