Let me say up top that I had a perfectly fine stay here -- it was clean and in a quiet residential neighborhood. All I was looking for was a place to stay for the night, and this did the job. A utilitarian but pleasant stay.
However, it was advertised as a guest house, whereas in reality it's a converted room with a backyard entrance through a sliding glass door. I could hear the residents through our shared wall. That wasn't a problem, but if you're expecting the privacy you get with a guest house, it's worth mentioning. I didn't need a lot of space or anything, as I was traveling solo and was only in the place for maybe 18 hours, but even still it was, uh, pretty cozy, let's say. Again, not a big deal for me, but it wasn't clear from the listing just how small it is.
All that said, if I'm in San Diego under similar circumstances in the future, I'd book this place again.