Not a fantastic hostel. Private rooms are missold as single... when they are actually multi-bed 'private' rooms. The dorm beds are very uncomfortable, the oldest mattresses and impossibily lumpy pillows. Had to ask specifically for a sheet. Staff are not particularly helpful either, couldn't help booking buses out of the city and wouldn't help book a taxi at 4 am in a dangerous part of town... had to wander around and find one myself. But it is cheap and in a decent location in zona 1.
It really is a basecamp for the hostels excursion business, but a great place to stay. Only real issue is the lack of a 24 hour reception, makes it awkward to check in and out when you inevitably arrive and leave early/late. Breakfast is decent and staff are friendly and helpful.
I was the only person staying there at the time, so the atmosphere was somewhat lacking. However it was very comfortable, clean and a good base to explore the nice city.
I had a fantastic time here. As a solo traveller there is a great atmosphere in which to meet lots of fun people and the staff are awesome. Location is good, and it just works. Totally recommend it.