I sat on the fence for a while as well -- I think many
DVC members will tell you the same thing.
I really like the concept but was not entirely able, at the time, to purchase. That was at OKW.
When I stayed at the Boardwalk later, I was really taken in with the place. And that was where they were selling at the time. I went to the presentation and found out how much the points were (which were much more than the original OKW points) and I thought to myself, "If I do not buy now, it will just be more expensive for when I do!"
One of the main reasons that I purchased -- aside from the prepaid vacation idea -- was to force myself to take a vacation on a regular basis. I'm one of these workaholic kind of people who tend not to take the time that I need. However, my sense of squeezing a penny is higher than my workaholism

and I take the time so as not to lose out on the money that I have paid into my dues.
And the program has made it affordable for me to go to Disney regularly as well. Looking at rack rates for the rooms, I would not be able to go as much as I do. At least not at the types of resorts at which I like to stay.
Is it getting more expensive to go on vacation? Yes. With rising fuel costs, the airlines are certainly charging much more. However, I make sure that I look -- beginning quite early -- for the best price and then I pounce on it and lock it in. When I go down, I let the Magical Express pick me up and take me back to the airport. No rental car. Just remaining at Disney.
With the perk of getting an annual pass at $100 savings, I purchase one of those as well and make sure that I time my vacations so that I get three weeks out of one pass. Another way to pinch a few pennies, or, in this case, dollars.
I know the program is not for everyone. But it sure has worked -- and is working -- for me.