Overall we enjoyed our stay in the apartment. There were some things that bothered us a little (e.g. the AC has a loud pump, the rooms could have been a little cleaner, the kitchen is a little shabby, we missed liquid soap..) but we felt comfortable.
The neighbourhood is beautiful, we found a lot of great shops (I recommend going to "Ecotidiano" - a gorgeous store with eco and sustainable products) and restaurants, the Sagrada Familia is only some minutes away by foot.
The communication with Gunnar was perfect, he answered within some minutes and was always helpful.