I travelled with a friend. We were both pleased with the bedrooms and comfortable beds, nice linens, extra fresh towels. We both worked some during our stay, and we had no trouble with the WiFi. We had ample work space (a desk in one bedroom, a dining room table in the common area, small table in the kitchen).
It's an older apartment that retains its older architectural features, but the kitchen and bath are modern. Everything was very clean.
Excellent neighborhood with two nearby Metro stations. Elizabeth is very personable and very helpful, and she is very responsive to messages on this site. I hope to return to Madrid next summer, and I will be looking to see if Elizabeth's place is free -- I would love to stay there again.