I had a fantastic stay at Jacquelline's apartment. For starters, as other reviewers have mentioned, you really can't beat this location - in the heart of Malasaña, yet next to Chueca & Tribunal/Justicia -- and right at the point of Calle Fuencarral where it turns into a pedestrian mall, so you can still find a taxi /get dropped off by car should you need to (rare, given the location).
The place itself was exactly as pictured/described in the listing, if not better in some regards. It felt more spacious than I was expecting, and I was most pleasantly surprised by the very large living room, with balconies looking out directly onto Fuencarral.
As for the most critical factors I look at when evaluating an Airbnb: there's a great shower with high pressure and no shortage of hot water; excellent, high-speed wifi with repeaters/routers throughout the place to ensure you don't lose access in some parts of the unit; exceptionally clean - the place had clearly been professionally cleaned before my arrival; and while I didn't interact with Jacquelline, all my interactions were with Gigi, who was truly a pleasure throughout my stay -- extremely responsive, flexible on check-in time, gave me privacy once I was checked in, except when contacted -- and she has a killer list of recommendations for places to eat/go out in the area (I've spent a few months in Madrid now and she had some of the hottest spots in town on her list, plus a number of places I had never heard of but loved).
All in all, a phenomenal Airbnb experience; I've already looked into availability at this place for my next stay in Madrid and will definitely book again.