Stayed two nights on the 16th floor.
Pros: Gorgeous rooms are congruent with the elegant lobby. Met with welcoming letter from hotel GM, a very nice touch. Comfortable beds, modern furniture, stylish artwork and a (small) plasma TV highlight the room, which is also a good size for Amsterdam. Great views of the harbor from almost any floor. Breakfast buffet was superb, with an impressive variety of hot and cold items. Away from the main road, there is no exterior noise to contend with. Oversized, well-lit bathroom with a large mirror, good shower pressure with immediate hot water. Top-quality toiletries, as one would expect here. Two fast internet PCs in the lobby with free internet and printing services was definitely appreciated. Nice card insert concept upon room room entry to activate lights; this energy preservation initiative should be adopted in North America. For a fast meal, there's a Subway restaurant about 200m east of the hotel.
Cons: Key card given upon arrival to room did not work. After 36 hours up and a long flight, this was annoying. Office chair and sinking sofa in the room were not terribly comfortable. Quality of staff is hit and miss, though the front line staff are evidently well-trained. Most working the breakfast were cold and indifferent. Upon check-in, they will try to sell you upgraded rooms; I felt the Glengarry Glen Ross 'ABC' mentality was pervasive here, and somewhat deceptive. For example, rooms with a "fully stocked bar" actually receive two cans of coke and two Heinekens for the entire duration of your stay, which is worth about $5 U.S., so be warned. For non-Europeans, you will find stepping in/out of the elevated shower rather awkward, but get used to it in Europe.
Unsure: Hard to assess the effectiveness of the soundproofing as I never saw anyone on my floor.
Overall, a pleasant experience with a couple areas for improvement.