The boat is beautiful and in a fantastic location. We were in a party of 7 people and there was plenty of room for us all to relax, eat and sleep on the yacht. The value for money is fantastic if shared in a large group. This accommodation is definitely a choice if you're looking for a unique airbnb experience!
There were a few issues, there were no working toilets on the boat which meant that we had to travel quite a long distance to simply urinate or do other things. I guess the value of the boat and beauty of the marina it is located in almost makes up for this lack of amenity. Almost. The boat is in the part of the marina which is home to expensive yachts so security is tight and one has to have a security pass to get in and out (which can be quite annoying if in a large group).
The hosts were pleasant and fairly quick to respond to messages. I didn't meet them in person but another guest did who stayed with us and they said that the hosts were very friendly, although they don't speak fluent English. We are in Spain though so we didn't have a massive issue with this.
Overall I would say this is definitely worth booking if you are looking for a unique, in-the-heart-of-Barcelona experience. Just beware that you might have to travel a while for a pee.