My wife and I stayed in Jen's home for 4 nights during our honeymoon, and we had an amazing stay her home. The amenities are more than adequate and are as-advertised, including a larger size bed and shower (note there is a washer but no dryer). The apartment is ~3 minutes walk from Gran Vía and the Metro, so it is very easy to walk or subway to all parts of Madrid.
However, the **BEST** part for us was the apartment's proximity to the Malasaña and Chueca neighborhoods, which were adorable and full of trendy (and much lower-traffic) shops, restaurants, bars, and cafes, a welcome and delightful reprieve from the often chaotic destinations in Madrid. If we could go back in time, we would have spent less time at the major tourist spots (Royal Palace, art museums, etc.), and more time exploring the lovely local neighborhoods around this apartment.