The tour was absolutely worth it. Ray was a great guide. Two little notes. The trucks are inside the gates which I was not expecting....so show up early to get through the entry gate, pay your $8 fee, and find the correct truck. It is a truck with bench seats in the back, not a Jeep. Just clarifying for you.
But, even with above, I still consider the guided version worth it. You do get to get into native only sections (since the guides are native), and you do get better insight into the features and history of the area.
It really is stunning.