I put one in about 20k miles ago, and 4-5 oil changes later I love it. Put one in my wife's car as well. I initially had concernes over it accidentally opening so I added the 'clip' to lock it in place but quickly found it wasnt necessary and havent used it in about a year. Itw as kinda PIA to put it on anyway.
Heck, I wish they made a Fumoto Valve for my motorcycle, I'd put it on there as well!