If it was clear what you were getting when you booked rooms at Apartamentos Mur-Mar, it wouldn't be so bad but most booking websites advertise this place as a hotel at hotel prices which it definitely is not.
My friend and I paid over 120 euros a night for a four night stay in February. for which we got a twin bedroom, sitting room, kitchenette and cramped bathroom. On the surface this sounds good BUT the place was bare, bleak, very rundown decor (plaster coming off the walls, basin and bidet coming off the walls etc) and the kitchen was filthy. No way is this up to hotel standard - it's not somewhere you'd want to go back to after trekking round the city to relax. This is around the standard of a rundown, cheap-end student hostel.
On the plus side, it's in a great location at the bottom of Las Rambla, next to the gothic quarter and just 10 minutes walk from Plaza Catalunya. But be aware that it is at the dodgy end of Las Rambla. You walk through clouds of canabis smoke from the guys hanging about the entrance and nearby canteen to get in and, at night, the single glazing in the rooms lets in all the outside noise which goes on until around 4am - motorbikes continually revving up, shouting, football chanting - on and ON!
While you could theoretically fit four people into this 'apartment' with two on the pull-out sofa in the sitting room, only do so if you are really happy to rough it. Don't attempt with children, for example, if you want the family to relax and get any sleep.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC