It's very much an individual case basis, but IMHO for most cases for someone that visits on an annual basis and prefers to stay in a moderate or better then DVC should prove to be a financial saving in the medium to long term.
At present(or over the last 15 months or so may be more correct) there have been some pretty aggressive discounts to try and get people to come visit and spend there money, it is still possible, depending on usage, to show that DVC makes financial sense, although it does need a little flexibility on the part of the vacationer/purchaser for it to be easily obvious. The bigger questions are do you believe that those discounts will remain as aggressive? and will Disney continue to offer them so far in advance? The recent signs are that the answer appears to be no, and many people who were planning trips for later in the year are getting a touch antsy that their trips may cost them a little more than they were expecting/hoping. Without those deep discounts being available the numbers start to swing heavily in favour of DVC. We've seen, IMHO, a very unusual set of circumstances ( a long recession but 9/11 coming when it did really hit the travel industry hard at a critical time) yet DVC has continued to be a massive seller, retain a healthy resale value and even in extraordinary circumstances still shows an economic value, IMHO that value can only improve as the economy recovers and ( God willing) we're spared any catastrophies on the scale of 9/11.
But DVC isn't only a (good) economic option for many people, it is about convenience, quality and a long term commitment to their future vacations. For many people it isn't just about saving money, it is what you can "buy" for the same amount of money had you gone the "discounts on rack rates" route. I believe many people take the view that by buying into DVC it enables them to get far superior accomodation than they would otherwise have been able to afford. It becomes a matter of taste and personal choice. A hotel room at Port Orleans, for example, is a perfectly adiquate place to stay while visiting WDW and does the basic job (somewhere to sleep) as well as a one bedroom unit at any of the DVC resorts. But I don't think ANY of the basic rooms at any of the WDW hotels hold a candle to any of the one bedroom DVC units from king size bed, jacuzzi, walk in shower, living/dining room and full size kitchen. Now if you put it in terms of what those respective units cost to rent from Disney, I doubt many people that stay in the regular hotels would choose to pay 2,3 or 4 times as much for that extra luxury. But if you were to offer them the choice of a regular hotel room or a one bedroom DVC unit FOR THE SAME cost I would think that the vast majority would take the larger DVC unit.
For some people DVC is about saving money for a similar vacation experience, for others it is about giving themself the opportunity of experiencing luxury and making their vacations just that little bit more special for the same amount of money as they would spend on a "regular" room. For anyone that doesn't think the larger DVC units are a little bit special, I suggest they take the time to do the presentation tour. It isn't a product that works for everyone, but if you take the tour and you're honest with yourself I don't think there are many people that would turn down a one bedroom DVC unit for a hotel room for the same cost.
IMHO, it's going to be a pretty one sided debate.