Every time I have tried this, I have been thoroughly gouged on the price. Literally, I've had to call my broker to release funds to enable me to stay. And then I've been thrown out of the room to accommodate a late arrival who had an existing reservation. The staff literally threw me out of the window into the sea surrounding the airport island and I had to swim ashore with my suitcase. All my essential business documents were ruined and I suffered a crippling pneumonia. It's happened every time so far and if it happens again I will be writing the manager a stiff letter of complaint.
What's more, they took a long time to post the points to my account.