The apartment is well situated half way between Sagrada Familia and parc Guell, close to Joanic metro station. You can find a few supermarkets (regular and bio) in the proximity.
We were welcomed by David even if we arrived a couple of hours before the checkin. We left our luggage and changed our clothes but had to leave the apartment until check in (it was being cleaned when we arrived). David did his best to explain to us the how to's, where to go, how to get there, even gave us a few tips on where to eat.
The apartment is great, it has everything you could need (well, except for TV in each room, if you're picky and into TV anyway..), microwave, espresso machine (works with Dolce gusto pads - there were a few available, we bought more when needed), water heater, air conditionning, all sorts of cutlery and glasses and so on.
It might be a bit noisy at times, being it's an old building and you can hear sounds both from the other apartments and from the street, but that's barcelona :P We were able to sleep well until 9 am and fell asleep around midnight since the street is not that busy except for the ocassional car / motorcycle.
All in all, it was a great experience, very cost effective for the 5 of us.
Thanks Alex, Thank you David, Thanks Sandra!
P.S. Be VERY careful about the hot water. It tends to get very hot...