Another DVCer here who is aboslutely in love with the DVC ownership and how it works, etc.
As others have stated, it is generally a poor use of points to cruise on points. There are some instances (as stated above) where it works out to be almost the same (value-wise) as cash to cruise on points. However, that is only under certain circumstances. The majority of the time, it does not make good points-sense to cruise using your points.
However, if you want to go through some extra hassle....you can rent out your points and then use that cash to pay for your cruise. This would be a much better deal than just cruising on points. But again, you have to jump through some hoops here.
As a general rule, the best value for DVC is staying at DVC resorts. Yes, you can trade out to all of these exotic locations that they advertise, but those locations are hard to come by (having to plan and wait 18 mos - 2 years in advance), and is still often more points than its worth.
We love, love, love our DVC....but the biggest limitation is that it really is best only for staying at DVC resorts. If you go to WDW every year and want/need larger accommodations, then DVC is a great choice.