Pros: The place is really clean and well decorated with plenty of comfortable seating, great clean bathroom area, kitchen with everything you would need, great wifi, washer and dryer, and two balconies on either side of the apartment where you can watch the sun rise over and set behind the Barcelona roof tops. Public transportation is also easy to get to and will take you to most parts of the city, and finally Daivd and Yannick are super helpful with anything you many need.
Cons: The roof leaks during heavy rains, parking a car near the apartment would be close to impossible (but you won't need a car in Barcelona at this place), if the neighbor across and to the right were on their balcony I'm not sure that anything other than steam would keep them from seeing you in the shower (though I think they were getting blinds installed the day after I was leaving), and if you have a heart condition or are really unfit you will have trouble making it up all the stairs to the apartment.
Overall I would say this is a good spot and you will enjoy your time here in Barcelona.