sodbuster,
I know the inventor quite well and even helped him a with final design and testing. (However, I have no stake in the company so my comments are based on my personal experiences regarding this stand.)
It is very comfortable, safe, and incredibly practical. It's great for quick setups and for areas where you can not or do not want to leave your stand in the tree. I wear mine even if I go to a fixed stand just so I can change location in a flash if the situation requires it.
Tree steps are still required, however, you won't need to be buying and lugging stands all over the timber. Another advantage is that you carry any scent out with you rather than leaving it in the tree where you sat.
From what I have been told, there were several good bucks harvested from the Treesuit this past season which will be on a testimonials page on the Treesuit website in the near future.
DC