My own experiences in SF has been positive. I've found people are generally very excited about what they are doing in life, optimistic about the future and most importantly, willing to lend a hand. (This is in huge contrast to the cut throat image of the valley in the media; while individual startups and industries within tech may be cut throat, I wouldn't describe SF tech world as "generally cut throat")
One thing to keep in mind is SF has a fair share of folks who move here for their first job. These people are just entering the workforce and are maturing more, not less, each day. I've seen some pretty radical transformations of the same people over 1-3 years. A lot of the portrayal of the Valley in the media is of a fixed non-evolving mindset, which again, is the opposite of my experience.