If you love Barcelona, or have always dreamed of spending time there, this the place to stay. As all the other reviews say its close to most of the sights, if not by foot metro is 2 min away. Born district, Gotic, la Rambla, plaza Reil are all walking distance.
My partner and I would spend a full day sight seeing then come back for short siesta and go back out refreshed ready for full night out. Right next door Rubi offers nice refreshing mojitos for 3.5 €, a great way to start the night!
The flat has all the amenities you need from kitchen to sound dock. Steve is very helpful for anything you might need. The only thing to call out is there is no AC and can be a bit hot in August. He does have a fan that helps a lot.
In terms of noise, there is some chatter from the people hanging out in the ally ways at night, but not too much to disturb your sleep.
It's an amazing place. I would go back again in a heartbeat.