We stayed here for 3 nights in a Deluxe Double Room with a canal view while visiting Amsterdam, and were very happy with our stay.
The location is fantastic - even with our big bags it was very easy to get to from the airport, and only slightly more difficult to get to the train station on the way out. It's near lots of bars and shops and for most of the trip we just walked everywhere - it's close enough to all the touristy / interesting things to do so. Also I recommend Cafe George nearby for food or drinks - very nice :)
Our room was spacious and had a fantastic view over the canal. We even had a balcony that looked out onto the water which was awesome. The people at reception were very helpful for any queries we had, helped us get our bags in and out, and they offer 24 hour room service with a number of reasonably priced snacks that can just go straight onto your room bill.
The other (more positive) reviews of this hotel are accurate, including the downsides. There is not much in the way of amenities in the room (no tissues for example), but they do detail what they have on their website, and the free wi-fi is a godsend. And they are very reasonably priced for central Amsterdam so it is understandable.
Also take note of the lack of air conditioning - I was glad to know about this before we went, so we could factor it into our decision, but it was fine. Amsterdam is not usually a warm city, and so when our room did get too warm we just opened the window and let the fresh air in (which was lovely anyway). If you're worried about bugs like another TA reviewer, you can leave the light curtain across the window to stop them coming in.
Also the staircase is VERY narrow as other people mentioned, and there is no lift, but this is central Amsterdam and is the norm for little places like this! It is something to be aware of if you have a lot of luggage, but not really something to criticise the hotel for.
We slept really well while here - while being central it is a quiet street, and we were not woken by any noise during the night.
One last thing to note - our bed was actually two singles pushed together. Because we'd seen this in other reviews we knew what to expect, and it was fine!
We would definitely come and stay here again if we came back to Amsterdam. It is a clean, comfortable, and welcoming hotel, with a great location and is really good value for money.