I can only speak from our experience. We did agonize whether it was worth it or not. We did the spreadsheets, visited the discussion groups, and took the tours at WDW. Even then we weren't quite convinced. What actually pushed us was more an emotional reaction than a logical fiscal decision. It was the reality of the quality of life my parents had as the result of poor health that prevented them from enjoying their retirement. I decided then and there it was time to go ahead and enjoy my retirement savings while still healthy enough to do so. Once that decision was made we purchased a resale at OKW and then a resale add-on. In the first case it was an overseas owner trying to unload so we received a good deal with a years worth of banked points. With the add-on the seller paid our first year's MF. It was just a matter of patience and finding the right deal fro us.
We have no regrets. Since we've worked our way up from absolutely nothing to a state of extreme poverty, prior to DVC we would stay in the most economical accommodations possible. Since we have 6 kids we couldn't get by with less than at least two rooms. (We loved the All-Star Value Resorts.) We noticed after joining DVC we ended up in much nicer accommodations and we actually stayed longer for about the same expense as we were spending in our pre-DVC economy mode. With two bedrooms and a full kitchen, living room, two baths, a jacuzzi, and a laundry room we felt like we died and went to heaven compared to our pre-DVC vacations. Initially we would purchase annual passes for the parks then stagger our visits so that we would get two visits out of each pass, purchasing APs every other year. Of course, now as DVC members we essentially get what amounts to a Fl resident discount on our passes. Now that we are close to empty nesters, only our youngest is still at home, we've altered our accommodations so that we have enough points to go twice a year. Of course we now do the AP renewals which also have a DVC discounted price. There are also discounts to various events, shopping, dining, recreation, and tours just to name a few. There is in-room free internet access for DVC members, and free movie rentals at the Community Center at the DVC resorts. Of course this is just scratching the surface. One thing to consider is that your basically prepaying for your accommodations as opposed to it being an investment or savings. So far, for us, the costs have remained relatively stable compared to the room rack rate we would have been paying had we not joined DVC. Obviously, in this economy, deals can be found at the rack rate. Unfortunately theses deals never seem to be offered when my DW and I can get time off.