When the weather is nice in Amsterdam, this is an awesome place to sit and get some work done. The cafe/restaurant is located inside the Eye film museum, but is accessible to everyone even if you aren't planning to visit the museum.
The views are great and the space is definitely workable (there's wifi and power outlets). It can get busy during lunch time and weekends. Some of the higher up tables are reserved for dinner guests after 5pm, but I believe the bottom area and the very top back area are always available. There's a small selection of lunch options, so you can get some food as well.
The easiest way to get there is to catch the free ferry (F3) just outside the central station. It's just a short ride and the ferry leaves every couple of minutes!