Had a nice stay here, with just a few shortcomings.
For me, the lack of a living room--you walk directly into the kitchen from the sidewalk--is a bit uncomfortable. In that sense it's more like a hotel room, but if you're on airbnb to avoid the hotel room feel, maybe that will disappoint. Yet, as small as the place was, I had a hard time getting solid Wi-Fi in the bedrooms, which was a mild annoyance.
More crucially, there was some noise during my one night, either from an adjacent bnb rental or the coin laundry outside my bedroom window. Finally, the furniture, in particular one of the beds, is not quite as nice as it could be. I had a tough time getting comfortable on the thin spring mattress in my room, although the other one seemed much better. The couch and table/chairs in the kitchenette are, at the very least, impractical.
All that said, I appreciated the cleanliness of the apartment, the thoughtful guidebook, and the snacks. I think it just didn't live up to my personal expectations.
If you're traveling alone, especially without kids, don't need to work, and have to be in this particular area (South San Francisco, not to be confused with San Francisco proper), I can recommend Vienna's place. Otherwise, you might look elsewhere.