Registration: Disney has changed how they handle race registration and while some do not like it and state it's a pain in the butt, I have never had any trouble with registering. It has always been a quick and easy process for me.

Crowds: As to be expected, it's Disney. I have never had an issue with crowd size on these race weekends and I have run most of the Disney race weekends between FL and CA.

Expo/Parking: The expo is nice and depending on your timing you may run into long lines but that is to be expected. Parking for the expo as well as the race morning isn't bad at all. You don't have to pay to park and if you are staying on property you can use the free transport provided by Disney to get to the race.

Course: Great course as you go through the different parks. Some spots you may run into bottlenecking issues but it doesn't happen often. It was really bad for the first weekend for Star Wars Dark Side but from what I hear that has been "fixed."

Management: I feel like these races are well managed and I have never had a single issue. Communication is sent out if anything were to happen that could delay or cancel a race.

DO NOT RUN A DISNEY RACE FOR A PR.
Disney races are not meant for PR's unless you qualify to run with the Elites you will be getting pissed off over the number of interval run/walkers. If you want to go for a PR then do yourself a favor and go with a different race series.

A lot of people do these races as a fun run. It is Disney after all. So as long as you plan to come to just have a fun run through the Disney property and parks you will have a great time.