It's pretty flat, since it follows the river the whole way. There are a few small hills between Chillicothe and Waverly. IIRC total elevation gain for the entire 105 miles is like 1300 feet. Wind and weather are typically a MUCH bigger problem in mid-May, so come prepared for those!
"I felt [the women's Olympic marathon] was as important as women having the right to vote, because talent, strength, and capability cannot be fully realized if there are no personal rights to allow them to be visible or be deemed significant in the first place." - Kathrine Switzer, Marathon Woman