This is a big, vibrant hostel. I'm 46 and so i'm much younger than the usual guest at the hostel, but this didn't seem to cause any problems or unusual interactions. Each evening there's an event like a DJ set, beer pong, etc. These events can get pretty loud on the first floor. I stayed in October, and the room could get too warm at times, but the window only opens a little bit. Late at night I was always able to hear people outdoors talking and could smell them smoking sometimes. I'd say it didn't affect my sleep too much and for the price i'd stay again. The breakfast is very extensive and high quality for 7 euros. You'd be hard-pressed to find croissants of higher quality outside the hostel.
I wish I had brought my own lock. If you need one there are vending machines on the street that sell a stronger model of lock than the hostel sells. The hostel sells a lock with two small keys for 7 euros.