Membership in the Disney Vacation Club is not for everyone. DVC can make sense financially -- assuming you would always stay in a higher-end resort and visit Disney on a regular basis. If you always stay in a value resort, then it definitely won't -- but that's not an apples-to-apples comparison. The DVC resorts offer deluxe amenities and room size.
DVC is not the
cheapest way to visit Disney -- staying offsite is the cheapest.
There has been much financial analysis of the value of DVC. They show that buying a DVC membership is a rational, financially viable option for some people: namely people with the cost of the initial purchase already sitting in the bank, who plan to stay in the higher-end accommodations at Walt Disney World and/or Disneyland on a regular basis.
With DVC, you are essentially pre-paying for years of vacations at a discounted costs. Think of how room rates have gone up over the last couple decades. Paying out of pocket for 50 years of regular Disney vacations will cost much more than DVC - DVC does save money. Folks who must finance their DVC purchase won't save as much, but they'll still save.
Here are a couple of links:
DVCNews.com - The essential Vacation Club resource! - DVCNews.com - The essential Vacation Club resource! MouseSavers.com - Disney Vacation Club A Financial Analysis of DVC Membership