Pros:
1. Frank is a very friendly and nice host, he greeted us on the first day and also allowed us to leave our luggage in his office due to our early arrival and late departure upon leaving. He also answered our questions and concerns during our stay in a reasonable time frame.
2. The location is very central. It is 2 min walk to the metro and walkable distance to the main attractions
3. It has AC, which is very helpful (when working) because the weather was so hot.
Cons
1. The bed was broken from previous use but no replacement was available (as per Frank). The bed frame was metal and bent down the middle, folding upon itself like a book. We initially thought it was the mattress but that was not the case when we lifted the mattress. This particular design had no middle support column which is a seriously flawed design. The lack of proper rest had a negative impact because we could not get a good night sleep during our stay.
2. The walls are very thin. You can hear every little noise from the surrounding apartment units. Everything from TV's blasting to people having conversations can be heard.
3. Due to poor ventilation there was a strong second hand smoke from the unit (or units?) near by. We would notice this stench upon returning from a long day exploring the city and inevitably the smell permeated into our clothes. Upon landing in Lisbon after our stay in Madrid, we noticed all our clothes smelled like smoke as we had left our luggage open while staying at Carlos and Frank's.
4. Be mindful that the hot water tank only allows for 15mins of hot water. This is cumulative with any hot water use in the apartment. Quick showers are a must.
5. The kitchen space is very limited and it was very difficult to prepare a proper meal. What little counter top space that should have been available is dominated by the microwave. In essence, there is no prep space with its current configuration. Also you can only use one appliance at at time otherwise you will blow the fuse.