The tour I did was led by J. Jo who was really quirky and fun. He sang us songs on his guitar at a few points in the Castro and Mission tour. What I really liked was that he did not pressure anyone to pay at the end of this free tour (although tips are expected). Most people gave tips, and those that did not seemed to be backpacker types and he was really cool with that. That was really refreshing and I think, giving this freely, has probably contributed to the popularity of these walks. At the end of the tour, we stopped at a couple of shops in the Mission. Again, there was no hard sell and the shops were lovely, though on the expensive side.
The tour itself gave me a glimpse into Castro and Mission, which are both artistic, dynamic neighborhoods. I would highly recommend this tour to anyone wanting to move beyond the usual tourist areas and wanting to explore the real SF and all the things that make it the fabulous city it is.