Overall the experience from check in to check out was very smooth. The apartment is large with 1.5 bathrooms, and 4 bedrooms, so I'd recommend it if you're looking for a bigger space for more people. The balconies were our favorite parts, and you can see the top of la Sagrada Familia from the flat!

Some things to be aware of however:
1. There is a late check in fee and hotel tax that was declared after we booked - was a bit surprising and added to the cost.
2. It's not super close to the tourist areas (except for la sagrada familia), which was generally ok for us, but we did end up taking a lot of taxis to get around the city as the area was very residential.
3. Noise travels easily in the building, so you have to keep it fairly quiet or you will get complaints from the neighbors. Not generally an issue as we were often not in the flat, but I didn't feel like I could fully relax with my friends and have fun.

Overall, good experience though - thanks!