I honestly think that every neighborhood in SF has a distinct feeling, but I would characterize Hayes Valley as being up-and-coming and young. The neighborhood features a lot of local, artisanal food places, in addition to expensive clothing stores. It reminds me of Valencia in the Mission. I don't think the Mission is comparable to Hayes Valley, but the Valencia area is it's own world. There are a lot of upscale, clean boutiques and restaurants there. SoMa might be comparable in the nicer parts. There are good restaurants and a lot of young people that live there.
