We stayed here for two nights in a 6 bed dorm in block C (booked an 8 bed dorm so we were happy). On arrival the reception/common area was good with couches, computers, tables, vending machines and a bar/cafe.
The room itself had a separate toilet and shower, narrow lockers (bring a padlock) and bunks with bedding ready for you to make your bed. The room was clean and the beds were sturdy so no creaking which was good.
Breakfast is great, a lot of variety with meats, cheese, fresh bread, jams, other rice thins and things, fruit, cereal, hard boiled eggs, juice, coffee, tea and yoghurt. It is included in your stay so definitely make the most of it.
Wifi is free but only available in the common areas. That's fine though as there are plenty of places to sit, and some power points to charge your devices. You can pay to use the Internet on their computers if you haven't got a wifi capable device.
Free walking tours depart from the hostel, and you can buy tickets to some attractions at reception, some at discounted prices.
The bar was good and you can get meals for reasonable prices. There are events there some nights, and also happy hour with 50% off some drinks.
Sadly we had awful roommates who came back very late both nights stinking of weed and talking and snoring loudly. I guess we could have used ear plugs! (They sell them at reception.) Unfortunately you never know what your roommates will be like, but it is the price you pay if you can't afford a private room. It was very expensive to stay here on a Saturday, so be prepared for that if coming on the weekend. Sunday was a better price! Not worth the money, but I got the picture that everywhere was expensive to stay in Amsterdam on the weekend.
The location was good, close enough to the things you want to see if you go for a wander, and right beside the park.
Some of the staff could be more polite (we witnessed one being quite rude to some girls who were having a problem) but it was a mixed bag - some were great too.
You can leave your luggage in lockers you rent downstairs. You can only use the luggage room if you're in a group of 10 or more or your bag is too big for the lockers. It's 20c an hour or something like that, so not expensive.
Overall this hostel was good. It definitely had a big hostel feel (it's big with 3 blocks of rooms), and a large variety of people stayed there. I'd recommend it to other travellers who don't mind big hostels.