One of SF's time tested spots, and it has passed the test for a good reason. 4 stars on Yelp is tough for a night club in SF since most of the people who like nightclubs don't like Yelping, and vice-versa. I personally like it because there are 3 levels, but only one of them is the dance floor, so the other 2 play the music at a level that allows you to have a conversation.
It's got a reasonable cover ($10 usually), stiff drinks, a fun 25+ ish crowd, and a very cool underground dancefloor. I play a tasteful and fun open format set here.