We stayed at Luis's apartment for 5 nights and it was great!!
The place is right next to all the night life area in Barrio alto, full of bars and nice restaurants.
It can be a bit noisy but when you stay on the second floor it's ok :)
It's located in the center so all the places to see are close.
The apartment looks even better in reality, big, really clean, comfortable and even has a big kitchen.
Definitely recommend to stay there!!!