My husband and I loved staying in Carlos' flat for our first visit to Madrid. It was clean, well-decorated and just like the pictures show. It also has laundry in the unit, which we appreciated, as we packed light. Carlos was super communicative with us during the check-in process, and has an entire book of recommendations with favorite spots in the neighborhood and Madrid (Don't sleep on Casa Abuelo! Tapas there were AMAZING.)
The Lavapies neighborhood is vibrant and culturally rich. If you're looking for a spot that's more touristy, this might not be for you. We personally loved walking around and exploring the sights that were more "off the beaten path." The flat was a short walk from the Lavapies Metro station, Reina Sofia art museum and other attractions, making it easy to hit all the hot spots.
Overall, we enjoyed our time and would stay at Carlos' again.