I rode it couple of weeks ago. Missouri has done a great job with the Katy Trail. Someone should get a medal.
In Sedalia the route gets a little weird as it goes through town, watch the arrows that are painted on the road or you can get turned around. The same thing goes for Boonville, keep an eye on the arrows. Those are the only two places I can think of that are remotely confusing, the rest of it is all trail.
I recommend a meal at Meriwether's at Rocheport. You can't miss it, it's right off the trail. And I'm sure you'll enjoy a stop at Cooper's Landing as the above poster said.
As of a couple of weeks ago there was one spot right before Mokane (eastbound) where the trail was washed out and closed. I had to jump on the highway for about a mile and a half to get around it, no big deal.
Have a great time. I did.