I've ridden on a couple parts of the trail before but I'm not up to date on which parts are finished. Make sure you have some good flat protection if you try it, there are a ton of those little stickers on the trail. The time I rode it with my scout troop I bet two thirds of the two dozen or so participants had at least one flat on a 50 mile ride, many people had multiple flats. Needless to say, I learned how to patch a flat tire that day.
Also, I have been on some parts of the trail that are really soft gravel, so there was a ton of rolling resistance. That may have just been a recently completed section though, so it still needed to get packed down.
Overall though, the trail has some interesting segments especially when you get up into the sandhills. And as was mentioned, if you decide you don't like the trail, highway 20 is an easily accessible alternative for most of the way.