We went here last weekend for a bachelor party in Scottsdale. I booked online approximately a month in advance. They do get busy so booking early is advisable.
It is about a 45 minute ride from Old Town. I contacted Thor (not exactly sure of his role), who was able to help us schedule rides back to from the desert. He was very helpful because Ubers/Lyfts usually do not come out that far to pick you up. I would recommend contacting him as early as possible to reserve your ride, if you need one. They give you everything you need when you get there (i.e. mask, helmet, goggles). I would recommend bringing a backpack for anything in your pockets.
The unguided ATVs were absolutely incredible. The ATVs themselves are either automatic or semi-auto, so no knowledge of using a clutch is needed. There are two practice/training courses which totally get your ready for the ride no matter your skill level. Our group ranged from unadept, first-time riders to guys that grew up on ATVs. I would say after training, most people will be fine. The most inexperienced had a great time. One of the most important tips is to manipulate the center of gravity of yourself and the vehicle.
The trails were unreal - absolutely awesome. The up and down and side to side of the trails provided a constantly changing atmosphere and a unique experience each second. I would recommend keeping an eye on your surroundings so you can be aware of other drivers, the width of the trail for passing, and the incredible views. I missed one amazing photo op on the way in, but caught it on the way back.
I would recommend this to anyone physically able.