We stayed at the Radisson Blu for 3 nights. It is situated on a quiet street in a fabulous central location (5 minute walk to Dam Square). The hotel lobby is expansive and airy. We were in a "superior" room with a king size bed - very spacious room; large bathroom and immaculately clean!
We included the breakfast in our rate - the buffet was quite good - choices ranged from a variety of fresh-cut fruits to yogurts to meats to cheeses to "made to order" eggs. It was more than enough to keep us going til a mid-afternoon snack. The bar was comfortable and afforded a great place to watch World Cup Soccer with other guests. There is a work-out area but as we walked and biked literally everywhere in the city, we never used it or visited it. The concierge staff as well as the reception staff were gracious and polite. We would certainly stay here again upon our return to Amsterdam.