The location, in Poble Sec, is really great. The neighbourhood is vibrant, yet cosy. Your hosts are friendly and take good care to see you're welcome. The house is exceptionally clean and comes with good amenities. It is close to supermarkets, bars, restaurants and Barcelona's main tourist attractions. It is accessible by public transport, and from the airport.
The flat is great for a short visit, but I would not really recommend it for groups of more than 3 (even though it would be possible). It is quite a small space, which requires group intimacy. [It is a bit smaller than it appears from the photos, and sound travels quite easily in the space] However, I recommend it highly overall.