Mark's place is perfectly located to visit and walk to any must-see attraction in Amsterdam. Of course, a metro is close and only 2 blocks away, as well as a tram. But, honestly, the location is so nice that you will want to walk and appreciate the scenery.
It is a very safe area, and even at night you will find the neighborhood lively (It's pretty close to the late night attractions of the city). The room in itself is wonderful, having every item needed that I could think of and extras of towels and sheets. Noteworthy extras: there is an electric kettle with tea and coffee ready to brew, a compact fridge, and an equipped stove.
The day view is pretty incredible, and the wifi works remarkably. As I checked in I got a brief introduction to our location in a map, and how to get to some hot points from the apartment.
Be warned that there are several staircases you need to go up, it wasn't a problem at all for me as I was packing light... but I know that some people might want to take that into consideration.