It's a nice place in a good location: near to parc guell and excellent transport links but there are some issues.
The flat felt very much like a commercial operation and it's clear to see there is some tension between the agency and the other inhabitants of the building. Our agent informed us of the presence of "noise detectors" in the apartment and that "we would get thrown out if we were seen to be too noisy". I considered this quite an aggressive start to the holiday and this could have been dealt with better.
The agency lacked some clear communication with us: on our arrival and check-in the agent informed us of a rise in tourist tax which we were due to pay. This was, however, written off once I explained that I was not informed of this and the agent agreed. Additionally, there are a number of potential extra charges that are not clear until you arrive (wi-fi, late check-in, late check-out) that should be communicated much better.
There a few finishing touches that are required for it to be the perfect home such as extra soap, extra toilet roll, bin bags, a dish cloth but they are by and large quite trivial.
The flat is excellently located near to supermarkets, bakeries and a couple of nice bars. The bus takes you into town or is a lovely 1 hour stroll away.
For an affordable option with a large group of people in Barcelona, there are probably few better.