There was one rock garden that I doubt anybody except a trials rider could ride but for the most part I would say that these trails are beginner to intermediate in nature.
The other annoying thing was the bridges. It was pretty damp and the bridges were treacherous, so if you happen there on a rainy day...and you can actually find all of the trails watch out for the bridges and the single board bridge that kind of jumps out of nowhere at you. No real penalty if you happen to miss it,at least that I can remember, but watch for it.
There are also several tricks and log piles to ride over as well. they are all ridable...even Steve managed across one without any mishaps.
All in all we had a really good time and supposedly there is a map of the trails that somebody has mad up and I am trying to lay my hand on one of these right now.
If you get the opportunity to get out to Yellow Creek to ride you wont regret it. The park is beautiful and I am sure that they will work harder to make the trails easier to find. There are plenty of facilities and the lake is there for an after ride dip.