Really nice apartment near the Sagrada Família. Host was very responsive.
Our card key stopped working on our last night, we panicked a bit but after the help of a resident in the apartment complex, we were able to get a hold of the host and communicate.
The beds were perhaps the worse, they were uncomfortable, two small (smaller than twin beds) beds combined, in each room. So as you slept and moved, one of the beds would move creating a hole between the bed, making you wake up and trying to fix yourself. Also there were stains that looked like blood stains, and oldness on the blankets and bedsheets.
One of the bathroom showers got the bathroom wet after taking a shower, with not mats, you'll need to use towels to avoid slipping as you exit the shower.
If you're traveling from the U.S.A - don't forget electrical conversion outlets. There wasn't any, although you could easily go to a shop and buy one, which we did.
There is air condition, so that was awesome.
There is only a washer, no dryer. You'll have to go to a washer/dryer shop - or hang your clothes out to dry, which doesn't feel good afterwards.
There were some bugs that were in the apartment on our first night.
At the end of the day, the apartment gave us a place to rest up, which was great. The above minor details, we combatted creatively. Perhaps the biggest issue was the beds, which is what you'd hope wouldn't be.