Karla's place is spacious, comfortable, clean and very conveniently located. The apartment gets great natural light during the day, and the large windows provide a nice view to the San Francisco street life. The place is big enough for two adults on an extended stay - with a large bedroom and closet for suitcases and clothes. Karla is extremely responsive and will make sure any problems are taken care of right away. We had an issue with the heater in the apartment, and it being Thanksgiving weekend, it was hard to get someone to fix it. Karla and Karla's uncle helped us - checking in with us frequently, and giving us updates on the situation and also provided us with a portable heater. They were able to get a technician when he became available and had the heater fixed right away.
The only drawback of the apartment is the tiny kitchen, but if you are visiting SF, I don't think you will use it very often. We did not and so the size was not a problem.
I'd definitely recommend Karla's place to anyone planning to stay there!