The flat is very comfortable and cozy and well-furnished. It's a ten-minute walk to Sagrada Familia and has several close metro stations to choose from to get to anywhere else in Barcelona. The kitchen is very well-stocked and there is heating/AC that you can set for the apartment so you're always at a comfortable temperature.
There are blackout blinds which are excellent for sleeping. During the day, you can hear quite a bit of noise from surrounding apartments in the building (footsteps, conversations, flushing toilets from higher floors), but it quietens down at night post 10pm so you can sleep. There was loud drilling/construction work that woke us up in the morning, but this is probably temporary so shouldn't be an issue once the works are done.