I've been going to KoC since early 2003. Through upswings and down in the number of people that go on a regular basis, changes in nightly themes, staffing changes and various stages of decoration, one thing has remained constant: the welcoming nature of the "regulars". While everyone has their own unique personality, there's a general air of acceptance, which is why people come from all over the Bay Area to a relative dive bar in the middle of nowhere. The drink prices are certainly not low, but they're reasonable and the bartenders are generally not stingy. While the men's bathroom left a lot to be desired before (as I see has been noted elsewhere), they've recently upgraded to an actual urinal. It's my favorite place to go and I hope the overall attitude doesn't ever change.
Of important note, while I called it a gay bar, the general tone of acceptance applies here too. On any given night there's usually a good mix of gay men and women, bisexuals, transgendered, cross-dressers, straight and questioning people. We've got 21 year olds and 61 year olds that come on a regular basis. I love that it's not pigeon-holed into one type of clientele.
Pros: Friendly customers, great karaoke, good sound system
Cons: Dim lighting, drink prices can be a bit high