From a yet to be member's perspective (as compared to a "normal" orlando timeshare:
Pros: - option to have almost guaranteed reservations at a WDW resort (with proper planning)
- Disney perks, including free transportation at the resort and to/from airport.
-disney magic, legendary groundskeeping and environment, cast member "attitude", etc.
-Proximity to other WDW locations. Walking distance to some parks, DTD, etc
-For now, the value of the DVC contract actually appreciates
Cons: -expensive! you can own a week for a 2 br at a five star/gold crown resort in the area for approx $5,000 and 650 maint fee per year. This is one third the cost of a week's worth of 2br points in DVC. Plus it doesn't expire like DVC.
-Limited usefulness outside of DVC. "Forces" you to stay in DVC properties for your vacations. (some may not feel this is a CON)

Outside of DVC trading power is subject to inflation and will lose value over time.
-Contract Expires. It is assumed that the market value of the contract will start to decrease near the half way point as the expiration year approaches.
Bottom line, If you enjoying staying on Disney Property in Deluxe accomodations and plan to do so for the forseeable future, then you'll likely find a lot of value. If you vacation habits are different, then you should take a close look.
The more I look at the issue, the more I see it as a non-money decision. Vacations cost money. Staying anywhere costs money. DVC costs money. Is this an experience I want to spend my money on or not. That is what I'm asking myself. I will say that I LOVED staying on WDW property this last January. It was my first time staying on site. It was at Wilderness Lodge. It was wonderful, wonderful, and fun, and beautiful, and the magic didn't end when we stepped out of the parks, and the kids loved it and there was so much to do, and the employees were so bright and cheery, and it was clean and it was relaxing......you get the point. I sold my Westgate timeshare. When we go to disney, we want to stay on Property. I can't afford to spend $300 or $400 hundered per night for 10 days every year but I can afford a moderate DVC membership and I'll still be using it when standard resort rates are $800 to $1,200 a night! That's where the payoff really is, 10 years or so down the road.
Good Luck