Location:
In a word, it was perfect! It was in an area where locals hang out and eat, so the "tourist" effect was significantly reduced i.e. better and cheaper food and drinks. And even though it wasn't in the heart of the tourist attraction area, it was a mere 10-minute walk to Las Ramblas. There was also a Metro stop a 2-minute walk away.
Hosts:
Rosa and Nicolas both greeted us on our arrival and sat the whole group down for a half-hour with a map. They explained where we needed to go within Barcelona, including tourist attractions and restaurant recommendations. It was so helpful! Throughout our 5-day stay, we were able to ask them questions and get IMMEDIATE responses. We could not have had better hosts.
Apartment:
The two bedrooms were perfect. One was on the smaller side, but definitely manageable. It had a window looking into the building courtyard. The other was bigger and had a window overlooking Parallel. It had its own AC unit. The common area was roomy, especially for Europe, and had a balcony overlooking Parallel. It also had its own AC unit. Although the small bedroom didn't have AC, turning on the common area unit for 10-15 minutes cooled the entire apartment, so it was no big deal. The bathrooms were small, but typical for Europe. The shower was great. There was a washing machine in the flat but no dryer. However, the provided drying rack worked well.
Overall, the stay was great and we couldn't have been happier!