We had an amazing time in Raul's flat. The flat has a small balcony, 2 rooms, one big bathroom, a fully equipped kitchen (all you may think of! dishwasher, washing machine, dryer etc...) and A/C. It is nicely decorated with pictures from Madrid and nice objects. Flat is really safe with 3 doors to go through. It also well connected to any part of Madrid with easy access to Metro in Sol. Not far from there is a nice monastery and the most famous chocolate con churros in Madrid.
The only negative part I could find is that it is a bit noisy at night on week-ends, beware if you are not used to the Spanish nightlife :) Nevertheless, the flat has really thick windows to cover it.
Raul was a perfect host and was ready to help at any time of the day. He even kept our luggage until we caught our flight at the end of the day.
All in all, I highly recommend Raul's place, it's perfect for any type of stay in Madrid! You wont be disappointed!