As a former Disney Cast Member, I was drawn to this race primarily because it is DISNEY. I'm a competitive runner from Chicago who is used to very structured races (i.e. Chicago Marathon). Overall, the WDW Marathon Weekend is very well organized, with the entire area fully immersed in the Race Weekend festivities.
The Expo- this expo is a moderately-sized event. It's held at the ESPN Sports Complex so the setting is perfect. A very wide variety of clothing, accessories, food/drink/fuel samples, and shoes. Getting my Bib and participant bag was easy and painless. Volunteers are on hand to guide you from point-to-point to get the items you need. I also enjoy the official race merchandise selection, which is quite extensive for men, women & kids. The race shirt is a long-sleeved Champion technical fabric shirt (Sizes runs small, FYI!).
The Walt Disney World hotels also are fully coordinated for this event. Each of the 34 resorts orders shuttles to and from the expo, to and from the race start lines/finish lines, and offers special food menus the days leading up to and the day of the races. (the special pasta dinner at each resort the night before the races is a nice touch!)
The Start Corrals are also very organized. You walk through a tent, drop off your participant gear check bag and are lead to the start line. It's about half a mile walk. The corrals are lined up on the highway so it allows for a lot of space. The corral assignment policy allows runners to enter their assigned corral or a slower one, but not faster, which is pretty standard. Be warned, there is not a wave start. They send each corral every 2-4 minutes and if you're in a corral further back, you will have to wait a while. I highly recommend submitting a qualifying time in advance of the race, no matter what your running level is, to get in a corral that suits you best.
The race offers entertainment- a band, a Disney character w/ photo op, or music and DJs every half mile to mile. This really helps make up for the fact that this is not a spectator friendly course. Since the course follows Disney's expansive roadway system, it's hard for a spectator to get to much of the course.
The marathon course takes you through all four of the Disney theme parks-- on stage and back stage too. Runners will definitely get a chance to see areas they would normally not get to see, which is fun!
The aid stations are well-staffed and offer the usual water and Powerade, with the later stations offering bananas and cold sponges as well.
The finish line energy is always ELECTRIC and includes lots of music and Mickey and Minnie to congratulate you! The medal is always on the large (but good large) side and really helps cap off a great race experience. The finish chute is filled with water and sports drinks and fruit, etc.

Overall, this race is one of my favorites. It's fun and definitely different than your community 5K experience! If you're a Disney fan too, you will hands-down love this race!