My girlfriend and I stayed in this hotel for four nights in April, at a cost of 99 euro per night for the room. We chose this hotel because of the good reviews and the very central location, just one block away from Placa de Catalunya, the biggest square in the city centre. There is also a Metro station across the street.
The room we got was a twin even though we had booked a double (the lady at reception told us that this was the only room left). We pushed the two twins together though and it worked out okay. The room was small but clean and, perhaps as we were on one of the higher floors, I didn't hear any noise.
One of the ladies who works at reception was very friendly and helpful, with good English, and put my girlfriend and I on the guestlist for a nightclub one night and even provided me with a paracetamol tablet on another night when I had a headache! The other staff members who we came across were fine too. The hotel is up one flight of stairs and there was someone on the main desk 24 hours a day so it felt pretty safe. The room rate included a continental breakfast which we only actually ate on one occasion. It was pretty much as one would expected - mainly toasts, a few biscuits and juices, that sort of thing.
So in summary I would say that while Hotel Marvi is not luxurious, for the price and location it is certainly to be recommended. If I return to Barcelona, I will probably stay here again.
P.S. The nightlife in Barcelona is great - check out the Gothic Quarter one night and the Port Olympic another. The latter is more upscale and expensive but also very good fun!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC