I had read the other very positive TripAdvisor reviews, and seen some of the pictures, and still I was blown away to walk into my private twin room: It was nicer than most hotels I've stayed in while traveling in Europe.
I've traveled in Europe for eight or nine months of my life, jumping from city to city, hostel to hotel, and my three previous hostel-stays in Prague had led me to expect a very different kind of hostel experience. I can't vouch for the dormitories, but the private rooms are quiet, well appointed, and comfortable at incredibly reasonable rates.
Central location for all the sightseeing and good eating you might want to do in the city, but not next to any large thoroughfares or loud tourist squares. If you want a hopping bar and live music those things are right on the ground floor; if you want peace and quiet and a good night's rest (as I did), the noise from elsewhere in the hotel doesn't permeate up at all.
Oh, and it's very environmentally conscious (both superficially and actually) in its ethos and design, so that should appeal to travelers worried about the carbon footprint of all their airline miles.