Four of us recently stayed for 4 nights / 5 days at Iryna and Oscar's and it was brilliant - the apartment looks great in the photos and certainly meets up to expectations in the flesh.
Iryna and Óscar met us on arrival to show us where everything was, explain a few house rules and point us towards their handy info book (phone numbers / wifi details / some tourist info etc). They were very welcoming and as our check in covered everything brilliantly we had no questions during the rest of our stay.
The apartment is well situated and made the perfect base for us to explore Madrid from. We would all thoroughly recommend it!