This flat is in a great location to explore Madrid, in one of the grittier, more artistic areas. Access to all the main museums is easy by foot.
The flat itself is really tiny and wouldn't be suitable for four people, in part because the main sleeping area is not separate from the living areas, so essentially everyone is sleeping in the same space with no privacy. As a couple for us it was fine.
The apartment is a newly renovated studio and consequently it was a little disappointing to see shoddy workmanship from whoever did the build: handles falling off things, cupboards not closing properly and a toilet that has been positioned half under the bathroom basin so you have to slide yourself in sideways to sit on the toilet and then sit uncomfortably a bit sideways while you're using the facility. The apartment also lacked a toaster or grill and so cooking options were very limited. The iron and ironing board were super cheap and frustrating to use.
The building lacks natural light and is quite dangerous to navigate during the day or night if you can't locate the automatic light switches. For what we paid, we were a little disappointed with we found. The location, however, is brilliant and the local neighbourhood a real treat.