I respectfully disagree. I think the Disney marathon is a great marathon for a first timer. It allows them to run their first marathon on a flat course with a very "fun" atmosphere rather than a race full of Boston Qualifiers (although you get some of those here too). If you put in the proper training, whether it's your first marathon or 100th, you will have no problem completing the Dopey Challenge. I would know as I'm one of those first time marathoners who competed the Dopey (and ran a sub 4 marathon).
Let's face it, the keys to completing the Dopey Challenge are to take it easy the first 3 days and save some energy for the marathon. The same is true for the Goofy Challenge...you need to save your legs on the half marathon to get through the full marathon. For me, I think the toughest difference between the Goofy and Dopey are the 2 added wake up calls on Thurs and Fri. The additional two races are not that big of a deal if you've put the proper training in.
In my opinion, the Dopey Challenge was a success and will continue on for many years. I think there are alot of people who did it and won't do it again because it does take away from your vacation (more so than the Goofy or doing one individual race). However, there are so many others that would love to give it a try and there are many who did it this year and will continue to do it again year after year.