I do not have any first hand knowledge about the Vacation Club, so I can't really say if it is a worthwhile program, but here is what I do know:
It is a kind of Vacation Plan with Points. For $5,000 you purchase a Silver Membership which will earn you 20,000 points. Your points are good for 5 years and can be redeemed for cruises (points required varies by cabin selection, length of cruise, and destination). Since you are idenitified as a VIP, there are a number of perks you will enjoy while on your cruise - such as special parties, welcome gifts, concierge services, a special embarkation lounge and pre-boarding privileges to name a few. You also get 2 for 1 air certificates or Free Companion Fare and 3 Land Resort Vacation Certificates (7 night stay for $299 for 2). It also includes a Family & Friends Program which allows them to make bookings under your membership. There are other components to the program - but that's the gist of it.