As others have said, this apartment is perfectly situated for all the main sites in Madrid as well as lots of local bars, shops and cafes. We found it easily with Domingo's excellent advice and he also had lots of tips and useful information for us. I recommend emailing before you arrive to iron out any details if you do not speak Spanish.
I would certainly return here and would recommend this place for other small groups of adults like our 5. We had everything we needed at a very fair price and found Domingo and his wife to be charming and thoughtful hosts.