Excellent experience overall. We started with a warmup climb to learn the ropes and the method of climbing, which takes some getting used to, and then the bulk of the experience is the time it takes to climb the main, big tree. There were only 2 other people in our climb, total of 4 guests plus 1 guide, and that felt fairly comfortable once we were up on the tree climbing together, especially if we were not all at the same height.
The views from the big tree are great; not a perfectly panoramic view but very much worth the climb. It does take some effort getting up there, and it is mostly a leg and core workout (you place your feet into some loops and push yourself upward along the rope, trying to stay balanced). There are several ropes leading up to the top, and each one has a different level of difficulty once you reach the branches; my wife got to scramble through a lot of branches which was fun for her, and I got to climb up to a branch that was nice and bench-like, which was fun for me.
Our guide, Isaac, is one of the most competent 18 year olds I've ever met and he made both my wife and I who are mildly afraid of heights feel very safe and prepared.