This is just my personal input ...
Pros: We stay on site now and use
DDP or DxDP, so our trip is essentially prepaid. That, in combination to figuring out which park we should go on which day and which restaurant we should eat at, make the vacation virtually stress-free. We were able to savor living "in the moment," kwim? There's just something about being at the Happiest Place on Earth that makes you forget about the world back home. If you're stressed out, it's a much welcomed break.
Visiting World Showcase. Although dh is military, we haven't really seen the world (only Portugal, Italy, and France). The World Showcase is wonderful in that it can give you a sampling of other countries. Sure, they might be a bit watered-down, but they're still pretty neat.
Cons: Disney is addictive. And it is expensive. But if you make your ressies early, you can make payments towards your vacation until it's paid for, so it doesn't seem so bad.
Like I said, Disney is addictive. Every time we leave, I want to go back. Sadly, this might be our last trip, as we're set to head West and I don't like planes. Our Dec 09 trip was nice, but I spent so much time planning (we took my mil and her dh for their first time, and I was so concerned about her having a good time) that I wasn't able to enjoy the trip myself. My dh said that this upcoming trip is for me. It's my do-over trip. He is so laid back that he really doesn't care where we stay, so he told me to pick my dream. We're staying Poly CL this year. I sent them my ADR requests, and we'll see what happens. Those are pretty much the only plans we have. We'll hit the parks at rope drop, have our ADR lunch, and wing the afternoon/evening. I'm usually obsessive about planning our days, but I think I'm really going to enjoy this experience. It's half-and-half to me. I plan half the day and wing the rest. Life can't get much better!
Sorry ... Didn't want to ramble. In a nutshell, Disney has many more pros than cons. I understand it's not for everyone. We've gone to Sea World and a couple of other attractions several years ago and enjoyed it immensely. A vacation is meant to be enjoyed, not stressed out over; otherwise, it's not a vacation. One year we hit the national parks in Utah. What an exceptional experience! Sure, it wasn't Disney, but we bonded and grew as a family. And we all were able to just relax and breathe and forget the stresses of everyday life. What can be better than that?