We stayed for 3 months, and I would recommend the experience with some caveats (see below). By far the highlight of our experience was the wonderful host. She consistently went above and beyond to find solutions to any problem we ran into, was extremely quick to respond to messages, and kind whenever we spoke in person. For instance, we work from home, and the owner supplied a desk in the second bedroom to facilitate this.
We've lived out of Airbnbs for the past year, and they fall into two categories: 1) homes that the owner lived in, and 2) rental properties. This feels more like a rental property for now. There are several quirks that no owner would put up with: unlevel living room tables, a surprisingly uncomfortable mattress in main bedroom. The exception is the second bedroom, which was very cozy and stylishly designed. I'm confident the owner will continue to improve these details over time.
The apartment suffers from a couple of intrinsic flaws. It's a classic California "motor court" complex with apartments immediately alongside a driveway. This means that windows are only available on the north and south, and the neighboring buildings are close enough that the apartment gets limited sunlight, even in summer. This is good for temperature control, but made us and our plants a bit sad. Also, the walls are very thin. You will learn the sound of your neighbors' alarm clocks. Note also that you will need to go to a laundromat.
Highland Park has a lot to offer. The apartment is slightly further to walk than ideal from the two neighborhood hotspots (~20 mins to York Blvd or Figueroa), but scooters can help with getting around. As summer went on, the neighborhood got more walkable, with lots of street vendors and food trucks around until late at night. The neighborhood is definitely on the bleeding edge of gentrification, and there is some tension between the established Latino community and the incoming stylish hipster crowd, but it felt safe and there are many beautiful streets and hills to wander.
Highland Park is also a great launchpad for exploring LA: You can drive to Downtown and the Arts District in 15 minutes or take the Metro, Pasadena is 10 minutes up the road, 15 minutes to San Gabriel Valley (best chinese food in the US), and the beach is still only 30 minutes away on weekends. And of course you're just a walk away from incredible Mexican seafood and excellent, cheap groceries from the neighborhood supermarkets.