I stayed here alone during my Euro backpacking trip in Sep 2009. I choose it because it was a hostel from HI and i knew that it would offer HI standards. The localtion is great.
The rooms are typical hostel rooms. The only difference is that the bathrooms are located in the rooms.
I stayed in 2 rooms. 1 for 8 people and 1 for 16 people. Both were good.
Remember, you are pay cheap rates, so don't expect 5 star hotel quality.
Also, bring a locker so that your stuff is safely kept and you can enjoy what Amsterdam has to offer.