The great thing was that it was self-selecting -- the less compatible types answered very few questions and stumbled over anything involving basic general knowledge, logic or ethics. The compatible ones added thoughtful or witty freeform comments to their answers. You could essentially clear all the usual first-few-dates compatibility dances just by running through people's answers.
I met many wonderful people via that site, and I never went on a bad date with OKC; we always had heaps to talk about. I thankfully found my perfect match for all time via OKC nine years ago, just before match.com ripped up the matching algorithm and the questions and destroyed the site entirely.
It is not a good business model to match people well, and match.com clearly knows that.