Our stay in Celesta's Airbnb was unfortunately cut short, but our time there was enjoyable. Celesta wasn't there to check us in, but her wonderful mother was very kind and helped us with everything. The Palazzo dello Spagnuolo is architecturally beautiful and impressive. The Airbnb itself had plenty of sleeping space and room for the three of us, but the ceiling is super low. I'm 5'8 and the ceiling was only 3 or 4 inches above my head. Wasn't a problem for us at all, but just a warning for taller people! Also the wifi didn't work upstairs, only in the downstairs area, so if you're very dependent on wifi you might have some issues.
The locals here are very conversational and kind, but we also encountered some unpleasant people during our stay. A random stranger spit on my friend's face for no reason, and a woman tried following us all the way back to this apartment and followed us all the way to the door. I don't think they're at all reflective of the people of Naples, but we didn't at all expect to have to deal with that.
Otherwise, Celesta's place is a great choice for a stay in Naples.