The flat was OK, but no where near big enough for 5 people. The third bedroom has no drawers or wardrobe and doesn't even have enough space to open a suitcase in the room. There was also not enough hot water for more than one person to have a hot shower... It is ok for the cost (compared to other 5 bed places in Madrid) but you definitely only get what you pay for!
On a positive note, the host was excellent - easy check in and great communication. When I expressed my concerns to her she offered us a very late check out for free which was appreciated.