Large, somewhat impersonal. Reasonably clean, comfortable rooms and beds. Terrible location - quite far from the city center, but at least close to several metro stops.
Bad location in a sketchy part of town and rather far from the city center. Perhaps this was only because we stayed here in the hottest week of the summer, but there is no AC and the room was very poorly ventilated with windows that barely opened, and it was nauseatingly hot - almost impossible to sleep. It is a large hostel, secure, and relatively clean, but staff is less personal than at others and there not such a friendly culture among the guests.
Quite clean, well-furnished. They do not run as many activities out of the hostel as others I've stayed at, but the staff were cool and helpful in showing guests where to go in town. Not a heavily party or sociable hostel if you're looking for that. Location is good but not great, you can walk to Pl. Catalunya, The Gothic, or the beach clubs in 20-30 mins but not recommended, especially at night.
Our stay here was fantastic. The best parts about the hostel are its location (in walking distance of nearly everything you'd want to do in Madrid, and within seconds of a metro stop), and the great vibe it has: tons of cool people were staying and common areas and activities facilitated meeting new people. The staff is great too: Patricia who led the pub crawl is the best. Only complains were that the bathrooms are a bit small, and you need to provide your own lock for the lockers.