It has it's perks. The jobs pay well (at least for me), even after cost of living. The weather is great year round. There's ample stuff to do. But it's dirty as hell, and the homeless are rampant and even aggressive.
I have lived in San Fran, Portland, Seattle, NYC, SoCal, Philly and Dallas. Only one of those cities I absolutely would not go back to. I even had a potential VP position at a large company there. Between the homeless problems, the smell, the commute, the cost of living, etc. it is the only city on my "never" list.