We (a young Australian couple 28 & 32) stayed in this apartment for 4 nights in October.
The location was great - in a very young and trendy district (like Darlinghurst in Sydney) with plenty of bars and restaurants, close to the Gran Via (about 400m), and an easy walk to most of central Madrid. There is a Metro station and a bus stop close by to get to the galleries, and buses to Toledo, Segovia etc leave from the Gran Via.
The space was ample for two and the house was clean and tidy. There is a very small balcony from the window, not big enough to stand on.
The bedroom was dark and quiet at night, and there is air-con in the rooms.
The bed was a double and very firm.
David is a friendly and kind host, it was lovely to meet him.