My two friends and I stayed for 5 nights in March. We arrived in the evening and had been given instructions for checking in which were very simple so all went smoothly. The apartment was as in the photos and was surprisingly spacious - usually you find that photos have been taken at a clever angle to disguise how small a space is. It was stylishly kitted out and clean with a comfortable sofa and two chairs. There was a large fridge and facilities for making simple meals (note there are no condiments/coffee/tea etc). Towels were clean and snowy white.
We were worried that the apartment was a bit far from everything but sights in Barcelona are spread out anyway and the apartment was 5 minutes walk from one Metro station and 12 minutes from another (and we are not fast walkers!). A bonus was a patisserie a couple of minute's walk, a bakery about 5 minutes away and a good supermarket 7 minutes away.
The host had an office on the ground floor and was available during office hours. He was very helpful and tolerant of our questions and helped to book to tickets for us.
We would certainly recommend this apartment to other guests. There was nothing we could pick fault with at all.