I had a great stay at Mercedes apt. She was very responsive, replied very fast, and even though we haven't met, she was very nice and polite. The check in and check out process was super easy.
The apt is completely renovated, so everything is new, modern, charming and clean. The location is good, very close to two metro stops which take you everywhere in the city in few min. It can be somewhat noisy, but nothing that earplugs won't resolve.
All in all, it's an amazing studio and definitely recommend it!