I spent 4 nights in Cipri's apartment in October 2017. The apartment is one easy bus ride from MAD airport to the main Atocha Station. From there, it's about .6 mile walk.
The apartment is very clean and fully furnished. Looks like it was just remodeled. Has a very large fridge and wifi is very fast. Heating and AC works very well. It is a .8 mile walk to the Prado Museum and only 2 blocks from the Sofia Reina museum. Plaza Mayor is also close by. Very centrally located and walking distance to all the attractions and restaurants in central Madrid.
The apartment is on the 4th floor so be prepared to climb 72 steps to reach it. No elevator in the building. However, it is very quiet on the 4th floor. There is no street noise.
Highly recommend staying at this apartment due to its location and cleanliness. It's well worth it!!