The stay in Pablo's apartment was quite good! Pablo himself was very friendly and helpful - he gave us a lot of suggestions, brought us extra (beach) towels when we asked for them, and helped with making our departure as smooth as possible. We could leave our luggage with him while we enjoyed our last day in Barcelona, even carried our luggage downstairs and called a taxi to the airport for us.
The apartment itself is as described and the pictures are quite realistic. We were 4 young adults and the apartment was quite small, but overall sufficient for our 5-day trip. It is a bit older (and less blindingly white) than it looks in the pictures but is well-kept and clean. The kitchen and bathroom was equipped with all necessities. In terms of location, the apartment is right at the foot of Park Guell which is very lovely. However, the climb up to the apartment was thus very, very steep, so keep that in mind when you arrive with your luggage. By bus/metro, it took at least 30 minutes to get to any of the major attractions (e.g. Sagrada Familia) or downtown to El Born or the Gothic quarter, and any of the beaches were even farther away (almost 1 hour).