Hard to find a better location ! It is the absolute best.
As for the apartment itself, it is super neat and as described in the listing. There is just much less light than in the pictures.
On the negative part, the check-in process is quite annoying as someone has to meet you in person, and they will make you 15€ extra if you arrive late.
But apart from this, great apartment and I definitely recommend it for a stay in Madrid :)