We stayed in the "family room" (2 king size beds, 2 ensuites and a mezzanine), which was lovely, but not typical of the dorm experience.
The room was very comfortable, with a micro balcony overlooking the pedestrianised Regina St. Breakfast was nice for a bread + coffee hostel breakfast: a pastry and cinnamon brewed coffee from the cafe downstairs.
The vibe of the hostel was nice, though quiet (we arrived Xmas day). The location is central and a short walk to the Zocalo. Street noise wasn't a problem for us, as we weren't overlooking 5 de Febrero, the busy street.
There is a nice kitchen, though no drinking water provided - which should be a given for any accommodation in mexico. Also, the security door on the ground level could definitely do with upgrading. There seems to be an occasional security guard on duty late at night in the absence of a stronger door.
The roof bar is nice and finished, though not operating during our Xmas stay.
Would definitely stay here again.