Hey, Tink!
Go to the FAQ area and there's a ton of questions answered. My short version is this:
If you go at least every couple of years, and if you stay in moderates or better, AND you think your Disney passion can last for you and your "descendents" for the next 40 years, it's definitely worth a peek. I won't get into the financial pros and cons, but basically you're prepaying vacations up front, and will ultimately get a significant bang for your buck, especially in light of the quality of your accomodations.
Check back here frequently! Ask anything. Folks in these parts are glad to help!
BTW, if you want the company line, go to the official Disney website.