Wish we'd joined the first year it became available. Best investment we've made. Once you get used to the apartment-style rooms, it is hard to stay in a regular motel room anywhere, not just WDW.
We initially bought the minimum number of points required, but bought more the next year. We now have enough points to get a two bedroom for 10 days a year (during value season) and a studio at Hilton Head for a stop off on the trip home. Gives us the opportunity to bring along family or friends who couldn't otherwise afford, or wouldn't pay, to go to WDW. And if no one goes with us, we can get a one bedroom for a couple of weeks throughout the year.
Up until buying the DVC membership, we didn't vacation much, and now we start planning the next vacation the day we get home from one! So it has been good for us as a family.
And with Saratoga Springs having the 50 year contract, you and your kids (or kids to be) will be set for half a century!
You do have to pay annual fees. But compared to what a large room would cost at WDW for the number of days we go, it is minimal. In fact, we could never afford to stay in a room like those in the DVC system. There are also several discounts much like the Annual Pass' discounts.