The apartment is exactly what it looks in the photos. The location is great and it is very near to a supermarket (three-minute walking to ALDI), surrounded by little bars, restaurants and stores (which may sound inconvenient at night, but the windows are very efficient when it comes to leaving the noise outside) and fifteen-minute walking to Barceloneta Beach. Metros and buses are not a problem of the city at all, so I would say all places in the city are easily accessible. About the apartment space, I think it is pretty small considering it can be shared by 5-7 people. You won't use the shared spaces a lot, but one fridge and two cupboards are far from being enough to be shared by 4 bedrooms, so you may have to keep food in your bedroom. Also, the bedroom is relatively small for a couple, unless both are minimalists and carry few clothes/bags with them. It is important to say that the toilette is shared between this room and another one (the shower is private though). Two things that bothered us were the cleanliness of the apartment - which was with grease all over the kitchen and stinking - and the maintenance, as we had trouble with water leaking from under the sink in the bedroom, mold in the bedroom (walls and furniture, mainly where it is hard to see, as under the desk), the curtain that fell during our stay, the door that can't be closed unless it's hardly slammed, etc.. When we arrived, the organization and commitment of the users in leaving everything organized and clean was hard, so we had to call them and discuss about how we could adjust that (and it worked, but it isn't a very nice thing to do, as it may seem you are an annoying person). It may occurs to you as well, so just be aware that the cleanliness depends on everybody, not only you (and that is not specific of this apartment, of course).
All in all, despite being very critic about the space, I think it is a good apartment, considering all the conditions mentioned above. I'm pointing things I didn't like about it, but that's because those are the things that can bother you from where I see it. Barcelona is a big and nice city, so I hope you don't spend most of your days in the apartment. For using it as a sleeping place where you cook a couple meals, I think it is a great fit if you can be able to adjust the organization with the other users. Also, Tania is a very considerate host, that answers quickly and tries to solve the eventual problems you have during the stay. I recommend the apartment mainly for people who are going to stay for up to a semester or who are in a transition while looking for other place to live in Barcelona.