We barely slept for two nights because the quiet hours were not enforced. It was very unpleasant, and my friend is now very sick due to exhaustion. Please make sure your guests are respectful toward those who need to sleep at night.
Isaac's is a great hostel to meet other travelers from all over the world. I stayed there for a week and was constantly making new friends. The atmosphere is very warm and welcoming, the staff is helpful and fun, and after just a few days I felt like I had made a new family.