I've been definitely LUCKY...first experience with the best host ever!
About the flat: great flat, extremely clean and tidy, located just a stone throw from Sagrada Familia. I stayed a couple of nights in a very nice and cosy room. The bed was really comfortable.
About Silvia: the best host ever; she gave me LOADS of hints about everything (restaurants, places, prices etc.).
I'll definitely contact her again for my next visit to Barcelona.