Be aware that it could be the first of many, many races you register for. After my 2011 Disneyland 1/2, I gave consideration to that race being a one and done for me.
Now here I am training for the 2017 Kessel Run, having run 2 runDisney 1/2 marathons, and 2 runDisney challenge events (10K and 1/2 on back to back days) since that possible one and done race.