I stayed here on my way to a meeting after flying in to Schiphol and it was a relaxing place to recover from jet lag and prepare my materials. The grounds are beautiful, as are the public areas of the mansion. If you are a big breakfast fan, the 20 euro breakfast is actually worth the money; it is a gourmet spread with everything from traditional Dutch meats and cheeses to adorable miniature donuts. The in-house brasserie is excellent.
Some practical notes: rooms in the modern wing of the hotel (much less expensive) require you to walk through the bar and restaurant to reach them and involve several flights of stairs (there are elevators, though you will need to take a series of them). The hotel is often used for conferences and thus the lovely older rooms in the main building may be off limits during parts of your stay. And DO NOT take a cab from Schiphol to the hotel unless you are prepared to pay 80 Euros for the ride. The hotel primarily caters to clients with cars but there is a small train station less than ten minutes walk away.