The Western Addition in San Francisco is actually known as one of the more dangerous neighborhoods in San Francisco--partly because of it proximity to the tenderloin. If you look at a crime map you can see that in the last six months for example there have been hundreds of assualts and robberies.
On the bright side, no murders here this year yet. Like everywhere else in this eastern half of the city, you should just use common sense and avoid high risk situations (e.g.,don't go for a walk alone at night, don't leave your windows open so everyone can see you, etc.)
