After reading this and this, I decided to purchase a 23andMe kit. Just shipped it off yesterday, so no results yet. But I can tell you with certainty that gathering the required amount of saliva was disgusting.
I read that they require a lot of spit to make it almost impossible to procure somebody else's saliva without their permission. But I thought it was still going to be cake for me. (My brother and I are chronic droolers, and I'm told by dentists that I have excessive saliva. TMI?) It doesn't seem like much when you first look at the vial you have to fill, but it took me a couple of (very long and gross) minutes.