We stayed with Pilar for one week. It's a really fabulous location as you're close to metro or can walk to the main tourist places like Grand Via, but you've also got normal neighborhood tapas bars and eateries. The supermarket is only 3 min away. It's also very quiet and safe.
Madrid is very hot in August so having air conditioning in our room is fantastic. The room and apartment, even though it's small, has everything you need. Pilar is a wonderful host and looked after us really well. We would highly recommend staying with Pilar.