The quality of the first round of food, it's Michelin star food on a barbeque (in my eyes).Always nice to hear.
So why are they legendary? Food or frolics?
After that the quality depends very much on whether I still give enough of a fudge to watch it cook or if something else has grabbed my attention. Usually that something else is supposedly being far too competitive at a game of garden football/cricket. Apparently "If 7 year old girls can't take a sliding tackle, they shouldn't be on the pitch" is an unacceptable attitude to this kind of event.