Been to Bong several times, although not for dirt biking. They hold model rocket launches on several weekends out of the summer, and the launch site is right near the riding area.
I've seen the "trails". If you have an ATV and it's your only riding option, go. They are wide open loops, not a tree to be found. Probably okay for a beginner, as well. More experienced riders would get bored quickly.
If you decide to go, call ahead. The trails can be closed or limited due to weather or special events.
I've ridden there a couple times. Not fun at all compared to a track. It is usually very dusty if you are trying to ride behind someone and it is almost completely flat. I'll only be going again if it is my only option.
I've been to Bong many times over the past 4 years and it seem's to me that it's going down hill . Don;t get me wrong it's a great place to go if your just starting to ride or get the kid's started, but if your looking for a challenge forget it .When its dry it's dusty and wet it's a swap .The Parkys treat the bikers like dirt but if you have a dog or horse or some other enviromently friendly form of recreation they roll out the red carpet for ya.My suggestion is to ride there if it's my last resort .