We booked the apartment at Clot Market, but on our first day in the apartment we discovered that the bathroom ceiling was covered in mold. After we reported this to the owner, we were offered to be moved to a second apartment they manage, which we agreed to.
The rest of the review is therefore not about this listing, but a different one in the Gracia district of Barcelona.
The replacement apartment was comfortable big, offered mostly the same benefits as our initial choice and all in all the stay was good. However, in this new apartment we discovered a leaking pipe in the utility room (we gathered water in a bucket over night and it was more than a litre of water that leaked over night) and reported this to the owners. They wrote that they would look into it, but we never heard back from them and the issue was not resolved until our vacation ended. Also the AC in the new apartment was not working reliably.
All in all I can't really recommend the apartments offered by this company - yes, they are on the cheaper side of offerings in Barcelona, but be aware that you might have to deal with issues when you choose to stay there.