Location is amazing ! We loved staying there, just off the Ramblas, right in the heart of old Barcelona, 4 doors down from a house designed by Gaudi (and yes you can get a ticket and see it). The flat is smart and clean and the automated check-in worked well.
Let's be honest it is in the heart of the town, so don't expected a silent night sleep, the street cleaners are out hosing down the streets at 5am, and still plenty of drunken tourists wandering around and talking loudly.
We loved it and it'll be my first choice when I come back next year.
They were super responsive , even sending an IT engineer over on a Sunday.