This is a great apartment in a really amazing location. It's not large - but certainly was big enough for our party of 6. There is only one bathroom (the toilet, shower, and sink are in separate rooms so you can have three people using each of these facilities at the same time). Also, the basement room can be a little damp, but a dehumidifier helps to keep the space pretty dry.
We loved our trip to Madrid and couldn't have picked a better spot location-wise. It's a quiet street in the heart of everything.