DIITO! I've done 3 WDW 5K--one was my very first 5K at age 46. I sorta do Galloway style but as I have lung issues, I walk more than I run.
YES DO IT AND ENJOY!!
Don't be put off by those who sprint by during the race and expect not all of them to be polite. Just shrug it off. I found some acting like it was an Olympic qualifier or something...geez......
There may be congested log jams on the route. Again, just relax even though you will find some shouting "COMING THROUGH!" and I rather wanted to trip them just for spite, but that would not be very nice.
WARNING: This mid life Disney running stuff can be highly addictive.

I started out never having run a step in my life with a 5K at WDW age 46. Age 47 I did the F&W Half Marathon and couldn't wait to go back again this year! Unfortunately a ruptured Achilles sidetracked my plans for 2013 from the half to the 5K, but hey, I'll be there!