It is pretty cheap. You can only book dates in the near future and even with sales there is really no other way to get rates that low for last minute travel. For example, right now you can go in March for 374 with the secret rendezvous but if you booked with the current sale for the same dates it would be 422 at the very minimum. The downside is that you don't know what resort or room you will get as they sort of you the secret rendezvous reservations to fill in the empty spaces. You could also use it to branch out to different locations if you are having trouble deciding.
We booked the Secret Rendezvous just this past summer. We got CTI and a gardenview room, which was well appointed and we liked it. Why book SR? The price! We saved about $800 and the room was very nice. We very much enjoyed the resort, and we got to do a day pass to CSS. We came back and booked CSS for March and we'll be there (CSS) in 41 days. Yahooooo.
CSA (07, 08)