We had a wonderful stay. The flat was comfortable and well equipped, with a well stocked fridge when we arrived. Margot was a perfect host, extremely helpful and accommodating, quickly responding to all of our queries, and even booking us a cab for the airport at the end of our stay.
Gracia was a great area - easy to get to the main sites, by metro or walking, but very relaxed and laid back with lovely bars and restaurants in the local squares.
I'd certainly recommend Barcelona, Gracia and this apartment to anyone.