This is one of the things that you must do if you have travelled to San Francisco. The views are fantastic. The clearer the day the better, as the more you will see. The view across the city is amazing; you can see the Golden Gate Bridge, Ferry's at Sea to Alcatraz and so much more.
We took photos for others and the same was reciprocated. There were plenty of signs stating to be careful due to thefts and police cars were near by should an issue have occurred, but there were no issues on my visit.