I took it in June 2019 on a round trip from Chicago to Kansas City.
Westbound we took I-55 to I-270 to I-70. It was ok but heavy traffic and a lot of hills. We had to change speeds often and was not able to use the cruise control.
Eastbound we took I-35 to US 36 to where it becomes I-72, then along I-72 to I-55 in Springfield, then back up I-55 home. US 36 was a long, mostly straight 4 lane road without a lot of cars or services. There were far fewer hills than on I-70. I set the cruise and let it roll.
I would take US 36 again without reservations.