I've been a couple times and went last year to show/stay in my camper trailer in their "Overlanding" area that was a new and last-minute addition (when Roxor backed out of their large vendor/test course area very close to the event.)
I've never been as a participant, however, so I've not been out on any of the rides except for one at the old location, nothing at the new one. I've stayed in the VERY large vendor area and watched people on the obstacle course.
The first thing that I hear about every year is the insane traffic getting into the event each morning. If I were to go as a participant, I would only do so if I stayed in the MASSIVE campground directly adjacent to the location. People tell stories of two plus hour bumper-to-bumper slogs to get to the location in the morning.
I walked the campground next door one night last year, I had no idea how incredibly huge it is. There were easily more than a hundred spots, probably a whole lot more. It was one giant party after another with lots of groups of folks staying together. I had a blast going from group to group and there were Jeeps "cruising" the roads through the campground just doing circuits. Definitely not a peaceful quiet camping experience, more like a NASCAR crowd or something. If you're off in a corner somewhere, it's probably fine, but around the couple ponds in the middle were quite hopping.
Second, I've always heard the trail riding is fairly basic and not technically difficult. Certainly seems geared to newer Jeepers and smaller Jeeps. I went on one ride in Matt's LJ at the old location when I was there for GR8TOPS and it was a very easy ride. There's an obstacle course, but I don't go for those and theirs seems fairly easy. They added mud pits, but I don't go for those either. They're miserably hard until enough people go through to get down to solid ground and then anyone can get through.
Third, the cruise-in downtown is a crazy thing to see and almost makes it worth the entire trip. This is definitely my favorite part of the entire thing.
Fourth, the Jeep history display is cool to see and it's neat to see the Bantam Jeep history plaque in town.
They've been adding more stuff to this like the powerwheels Jeep downhill race, night runs, etc. I walked up to the LED light contest last year and it was the dumbest, worst, stupidest, most god-awful, horrific thing I've ever seen at a Jeep event. Purely celebrating the worst modification you can make to a Jeep. I wanted to throw up.
I don't know what anyone will take from that combination of comments, but that's my contribution. I'd put this in the "vendor show with trail rides" category as opposed to a trail riding event that has a vendor area.