The apartment is lovely, and exactly matches the pictures. It's a modern, bright, clean space and was the largest studio we've stayed in. The location could hardly be more ideal, with all the main attractions of the Centro being 15-20 minutes walk away and a metro station at the bottom of the street. Being an apartment in the centre of Madrid the street outside never really quietens down. While this didn't bother us if you're a very light sleeper you might want to pack earbuds. Being in the centre of town you're obviously surrounded by shops, cafes, restaurants etc and you do really feel like you're staying in the heart of Madrid.
Israel was really helpful - always very quick to respond to messages, accomodating and made travelling from the airport by metro really easy by emailing us a pdf with directions and maps beforehand.
Overall it's a great apartment, and we'd definitely stay again :)