This is very interesting. I just moved to San Francisco from Beijing, myself!
I got here at about the beginning of the month, stayed 3 days in a hostel, 4 more days at a friend's place in Oakland and then signed a lease for a place in the heart of Chinatown. It's a fairly small room and the kitchen and showers are shared, but at $500/month all my acquaintances are saying I got a fairly good deal.
My trick was I got the landlord's number from a friend in Beijing the week before I left. Having friends in Oakland was just total luck. I'd met them years ago in Taiwan! All in all, Chinatown is pretty nice. It's safe, there's a ton of fresh produce to buy all over the place and things are cheap.
The two things which would be downsides for some are the hilliness and the Cantonese speaking community. I hated the hills when I was carrying my stuff across town, but now I generally appreciate the exercise while walking and the fun while on wheels. I do have a huge advantage being literate in Chinese characters, and Mandarin is more useful than English in a lot of areas, which mitigates some of the issues being surrounded by Cantonese.
I'm not working yet, but I've been going to a lot of Ruby and JS meet-ups, and it's generally a sub half-hour walk to any of their offices. All in all, I like it. I just have to avoid the Tenderloin when coming back from the Adobe/Zynga area.
So far the only difficulties I've had have been general country adjustment things (having spent nearly my whole adult life abroad), not SF things. To be honest, I'm amazed at how friendly and helpful everyone is!