My wife and I had a really nice stay at Jon's place. About a 15 minute walk to Gaslamp. Jon's place is very cozy and very well decorated, and the area and building felt safe and was quiet at night. We went during a heat wave so it was nice that the AC and ceiling fan worked really well, kept it pretty cold all night. All the amenities worked without issue.
We had two issues, there were a fair bit of ants and bugs that kept finding their way in but we couldn't figure out from where. Was more of an issue for my wife than myself.
The big one is the size. The pictures make it look a lot bigger than it is. The whole Airbnb is about 10x15 feet with a small bathroom attached. It's essentially a dorm room. That was fine for the two of us as we really only went back there to sleep. There is very little room for luggage, so if you have a bunch of suitcases you're going to be cramped. That being said, it's pretty expensive for what you're actually getting, but so is literally everything in San Diego.
Overall, we had a pleasant stay and Jon was an excellent host.