I think its fairly genius. A great way to meet new people. Takes the pressure off. You have your friends, they have their friends and everyone goes in with little expectation. Those are ALWAYS the best situations.
So you become a "member". Fill out a few miscellaneous questions regarding how important your race is to you and tip your preferred age scale between Hugh Hefner and Beiber and you're practically set. Grouper looks at your Facebook page to pick your grouper partner (I am convinced all they look at really is geographic location and age) and then both people bring 2 wing-people. You receive the location and time the day before (groupers are always on Thursdays, and normally at 8 or 8:30 PM).
Your job is to show up, meet new people, and have a great time.
The real genius difference between Grouper and anything else out there is Grouper facilities an actual meet up. Schedules it, picks the place and its easy. Seamless. Convenient.
I totally reccomend it.
For more info, and a better explaination than mine check out their website.