My preference for youth hostels us usually for the small ones in the middle of nowhere. On the other hand, this purpose-built facility couldn't be nicer. Convenient to the both of the rail stations, with many small rooms, overlooking a typical canal, offering a convivial bar and dining room, and very affordable (in an otherwise pricey city) who could ask for more?
If you're planning a trip, be sure to use the Dutch youth hostel's website http://www.njhc.org/english/default.cfm) to make an advance booking. That way you can request one of the many small 1, 2, or 4-bedded rooms. The rooms remind me of a roomette on a train: very compact, but very comfortable.
This is one of the best city hostels I've ever been in (and I've run one hostel, and stayed at quite a few more).