So, now I'm back home.
Review as I promised:
Hostal Centric is situated a few minutes walk from Plaza Catalunya, near "everything" and easy to find. I stayed in an "economic" room, with shared bathroom - that's always a gamble, right?
The bathroom (shower) was shared with two other rooms, and it was spotless!
Room itself was small, but as my nephew said "we're not spending too much time in the room anyway"... It had a miniature balcony, which we used as fridge.
For the price (42 € per night, booked through hostelworld, the prices on the hostal's own site is higher, maybe the season changed?) I think we got a nice room.
It's not a party hostel, but the walls are thin so we were woken in the wee hours by one drunken neighbour.
no breakfast but finding a café in Barcelona is easy-peasy
All in all we had a good stay, a middle aged auntie and her 15yo nephew.