I bought one last year on sale at Summit. I've used it on a hog hunt in SC and just the other day here in PA for deer.
Advantages: Extremely simple to use, just lean it against almost anything, takes a second to set up. Easy to carry either in hand or with the carry strap. Dead quiet with no moving parts or popping bark from seats and ropes settling in. Very easy to shoot while seated and standing up is zero effort unlike some other seats.
Disadvantages: Small firm padded seat that limits sitting duration (I added more padding with several rubber bands). I stand occasionally anyway so it's not a big deal. At 4lbs it's not all that heavy, but I wouldn't want to carry one on an all day hunt. I've been thinking of making one out of aluminum at work, just haven't got around to it yet.
You should see my collection of seats hanging on my garage wall. All have pros and cons. The treeseat is simple, quick, quiet, and user friendly. Not perfect, but pretty close.