We had a comfortable stay at Enrique's apartment. The apartment is exactly as advertised, so no bad surprises. The El Rastro fair is literally at your doorstep - it's a very nice experience - and the La Latina neighborhood, where the apartment is located, has a chaotic charm of its own.
We had no problems for checking in and out and were undisturbed during our whole stay.
I would definitely recommend it if you want to experience this side of Madrid.