Located in a very nondescript, locals neighborhood in a likewise building, what the apartment may lack in size, it makes up in comfort, classy design, expected amenities (no dryer aside), and beyond great communication.
A five minute walk from the Atocha train station (which we arrived and departed from), two minute walk to the Reina Sofia, and maybe a 15 min casual walk to the Prado - the location (for that side of town) was excellent. The direct neighborhood/street is definitely a locals spot so if you are expecting tourists to be outside your building and hanging at the cafes/restaurants on the sidewalk, this is the spot for you.
Comfortable for a family of four considering luggage etc - at least in our opinion.
All-in-all we really enjoyed the apartment!