We used a combination of points and cash once. A downside is that the value of your points varies considerably by the cruise you chosse to go on. On the one that I used the points for, I was able to calcualte the value at about $9.75 per point. Not the $10.00 I could have rented the points for, but close enough not to go through the hassle of renting.
The biggest downside besides point value is waiting until 11 months. Through a
travel agent or
DCL you can now make cruise reservations through 2005. With
DVC you can only make them 11 months out, which may limit your coice or level of cabins. Another downside is the lack of discounts or specials that those paying cash seem to have available to them.
HBC