Highly recommend that you use the porta-potties before you get into your starting corral. Friends and I walked to our corrals roughly 30 minutes before the start of the race. Organizers did a great job of making sure that runners were in the proper corrals. Unfortunately, as corrals started moving towards the start runners had to jump over the barriers to get to porta-potties.
This course is challenging with some difficult hills along the course, especially on the back end of the course. The front of the course is relatively flat with one hill near the beginning as you approach the Contemporary. However, this is also one of the parts of the course where it gets narrow and difficult to pass. Another section that is difficult is between miles 7 and 8 coming out of the back of the Magic Kingdom, pass the Grand Floridian, and returning out to World Drive. This is also where the sun and humidity seemed to drain me this particular day. Coming down World Drive is also the last flat section of the course until just before the Mile 12 marker as you approach the EPCOT parking lot. You are first presented with a curved hill exit ramp where the Green Army Men motivate you up the hill. You then cross a bridge and face two more hills that bring you back to EPCOT. Once you make through these hills you reach the throng of supporters that line the last mile to the finish line. And once you make it to the finish line there is Mickey Mouse and Princess Minnie Mouse to greet you.
One of the nice things about the Half and the other races is the ability to have your race time engraved on the back of your medal after the race, but remember to bring cash!