Carlos is a really nice and helpful host, the comminication was almost immediate and he gave some really useful tips. He also helped us in two urgent situations when we needed in immediate scan of a document and when we had a problem with the door locked with a key inside. Just for your information, as most doors in Spain have this sort of automatick locking system be careful not to leave a key inside when you go out.
The location is pretty convenient, we could reach all places we needed on foot, and it was nice to be close to Atocha if you plan to use a train.