Honestly, I don't see the big deal. Looks like something I'd never use.
For ground hunting I either use my Niff-T-Seat or sit on a log, rock, stump etc. I prefer to get low to the ground if hunting from the ground and this hammock thing looks like it keeps you up higher than I'd want to be. Might as well be standing. Standing would provide better shooting mobility too. Also, how hard is it to find two trees the right distance apart? I like a portable seat that can be put anywhere.
Now, in the interest of keeping an open mind, I'm wondering if maybe you could tie one end to a tree about two feet off the ground and the other end to a stake in the ground at a distance that would hold it with just a little bit of slack. Then maybe sit part way up from the ground and lean back like in a recliner. Sort of a hammock back rest? Of course, it'd be tough to shoot a bow from that position but not a rifle. Might be good for turkey hunting.