The apartment is great - clean, cool (which is good when it's hot outside), it has everything that is needed for cooking.
It is located on top of the hill, right near by Gibralfaro castle, it's pleasant to start your day with nice walk through the park downhill (~1,7 km pedestrian path), but after day of hiking or walking around the city it can be hard to go back up hill. You can use autobus (~1,35 eur per person) or rent a car (for car there is a spot across the street to park for free).
It takes ~10 mins to go to the beach and ~20 to the city center.

We've been met by Alvaro's brother Paulo, who was very nice and friendly. He also offered us a ride to supermarket on first day, that was very helpful as we did not have a car.

Overall impression is very good, we had a very pleasant 1-week stay at this apartment and can recommend you it if you are ok with walking up and down.

Btw, living there you can be first visiting Gibraltar castle in the morning (while it is empty).