This is a really cool apartment and is just 20mins walk from the sagrada familia and reasonable walking distance from many other tourist spots, the area itself is packed full of good places to eat. The traffic noise is minimal thanks to the soundproofing, but if you're a light sleeper you should take ear plugs due to the lift being the other side of the wall to the bedroom and the upstairs neighbours having a very loud toddler! We felt very safe though as the building seems really secure.
We had a few issues getting into the place as we arrived late and had to pick up the keys nearby and weren't sure which apartment was Laia's, the electrics were a bit off and we had to reset the fuse box everytime we boiled the kettle and struggled to get a bath's full of hot water, the air on/heater didn't seem to work but the standing heater was decent. All in all a good place to stay but an apartment guide to explain how to reset the fuses etc would have been handy! Though Laia was very apologetic and said she will fix this so hopefully future guests won't be affected and the bed was super comfy and the place was clean.