They can be used with much success!!! I hunt in NW TX and we have not trees, except on our creek, that are big enough for ladder ot climber. The best set-up is with a tree taller than the tri-pod behind you and a smaller tree to tour knees in front of you.
Meaning my set-up is between 3 trees. Tall to my back, short in front, and luckily another to my Right. Another stand we have is set in a big tree and then trimmed the branches as little as possible to have some shooting lanes.
If you cannot get set up like this, we have modified the shooting rail.....splying it out and widening it.....and the wrapped it in camo netting...preferrable leafy material. Then we cut some nearby veg and wire tied it on. What you have to have is a broken background and it is nice to have some vegetation between you and the animals.
I have taken hogs, deer, turkeys, coyotes, and bobcats without being seen but then again I have also been busted a time or two.
Good luck,
Kyle