I just stayed two nights. I would not stay again.
On the plus side, the staff is very nice and helpful. The location is also super convenient - transit to just about anywhere you want to go is available from Centraal Station, a five minute walk away.
My two big issues here are the rooms and the lounge.
They were booked full for the weekend so no upgrade for this Gold. I was given a queen room on the "executive floor." The view was straight into adjacent rooms:
The room was absolutely tiny - I suspect under 200 square feet. The bed - supposedly a queen - was smaller than a US double. It was also very hard. Here's what the room looked like:
Note the lamp in the corner was not plugged in - no outlet within ten feet. Nice planning guys. Also, the space looks bigger because the bed is so small. If you are six feet tall, your feet will hang over. I will add that the iMac as TV was for me unsatisfactory. The screen is very small. You can barely see it from the bed.
Breakfast was in the lounge. It's a nice space but it can't handle the crowds. Don't even bother going after 9 a.m., it's a total madhouse. Quality was mediocre at best. The fruit consisted of some brown pineapple and some watermelon. The smoked salmon was inedible. Baked goods were okay, not great. Very small selection of meat and cheese. Three juices. The coffee was not very good (inexcusable in this country where the coffee is usually excellent).
My advice is, if you stay here during the summer, pay up for an expensive room or you may get one of these prison cells.