We stayed here with our 4 kids, ages 4-12. There is plenty of room for a large family or a large group of people. Our host Alicia speaks fluent English. We were allowed to check in early on the day of arrival which was much appreciated as it gave us an opportunity to grab a nap after a red-eye flight without too much sleep.
We had the misfortune to come while there was some major construction going on either within the same building or right next door. This is of course no fault of the host but at times we could feel the whole apartment shaking. We were shocked to around 1 AM to hear more loud banging and realized construction workers were throwing debris down to the street below. Then at 2 AM the garbage truck came by making trash pickup (which is apparently the usual time for this neighborhood).
The other noise issue was from within the apartment. They have a heating unit in the middle of the apartment which runs on pellets. You (the guest) have to periodically push the pellets towards the hopper (auger) in order to make sure the heat stays on. we ended up doing it every few hours -- because we didn’t sleep all night. The biggest problem is that the heating element pulls the pellets down every 15 Seconds and this sounds like someone shaking pebbles in a tin can. If you are a very deep sleeper or plan to come when there is no chance of needing heat at night then this won’t be an issue for you. If you plan to need the heat, maybe bring earplugs to sleep. I had asked a few weeks before arrival if there would be heat and was not told anything about the noise that the heater makes. Again, since the heater is in the center of the apartment, the noise is heard everywhere. So I strongly suggest you ask the host whether or not this issue has been addressed. For us, they had no solution to offer for the noise so we were forced to scramble and find a hotel and check out early.
We were warned by our host to keep the windows closed or else stray cats would jump into the house!! We made sure they stayed closed but coming up the stairs to the apartment -- the first and only night we stayed -- a black cat did in fact jump out, scaring my wife and kids.
The house is filled with art which is of course a matter of taste. Some of it is quite graphic (eg. a large bleeding head) which gave our kids the creeps. There is a hammock in the house that my kids thought was great.
The neighborhood -- Lavapies -- has some lovely markets and cafes. However, all 3 of our tour guides in Madrid independently told us they were surprised we were staying in Lavapies because they found it possibly unsafe.