We usually stay about a week and have never spent more than $1500 on a hotel room for that length of time.
It won't save you money, for sure. But...
2) it changed the way we vacation. For the better. I may not be saving money but we vacation more, stay in better rooms, and share with our family. This alone is worth it, IMO.
This is why we got into timesharing, and it has led to awesome vacations. Our minimum size for the four of us (parents, DD16 and DS14) is a 2BR/2BA condo, and we're getting to the point where a 3BR/3BA is preferable when we can get one. Nearly every vacation, no matter where we go, my wife and I will look at each other and have the same thought: "Huh. People put entire families in a single hotel room." Usually, that's while we are sipping wine on the balcony, or maybe in the comfortable living room while the kids are asleep.
So, you won't save money, but as others have said, you might get decent value. A DVC purchase could make sense if (a) you imagine Walt Disney World to be your primary vacation destination for the foreseeable future, (b) you generally won't consider staying off-property, and (c) you can comfortably afford to pay cash for the purchase. It makes even more sense as a resale purchase, IMO.
We ended up not buying DVC, because we weren't sure Orlando was our primary long-term destination. We also don't necessarily need to stay onsite for WDW trips, though we do when an exchange opportunity presents itself. We bought resale, and so our total costs have been very reasonable. We've had some awesome vacations over the years, and I would go back and do it all over again, almost exactly the same way. We've used our timeshares in a wide mix of destinations: Anaheim and Orlando for Disney, but also the Wisconsin Dells, the Smoky Mountains, Hilton Head, Sedona, Washington DC, northern Michigan, and Waikiki. Next summer we have a trip planned with a week in a 3BR ocean view penthouse at Hilton's Lagoon tower on Oahu followed by a week in a 2BR condo at Hilton's Kings Land in Waikoloa on the big island. We've also given friends and family members weeks as gifts over the years.
I think our other reasoning is that we go to Disney for the Parks and experiences, not so much the hotel. While I love the deluxe resorts when we stay in them, in all honesty, we are rope drop to park close people. The hotel\resort is a place to sleep, LOL.
True confession: I'm a Founders Club member of the
Bay Lake Society. There is a LOT on offer beyond the theme parks, and it is worth it to explore. It's hard to imagine doing this in the first few years, but once the parks become a little "been there, done that" you will find yourself looking well beyond them. For example, my most recent WDW trip was just my son and I for Easter Week this year for a "boys' week away." We stayed in a 1BR at OKW, and happened to luck into Building 45, with a canal view. We spent several afternoons reading on the balcony, watching the boats go back and forth. The highlight of our week was a golf lesson at the Palm over by the Grand Floridian (neither of us play, so it was a first for both of us) followed by a late breakfast at Kona cafe. We also managed to snag a Nissan 370Z on the Emerald Aisle, so we spent some of our time just cruising around. We had plenty of theme park time, as well, but that's not all we did.