Wolfred, mate I used them in the Uk a lot, shot many a fallow and Roe from a high seat. There are many ways to use them and hundreds of designs.
I had a really nice portable one but left it there on the estate for all to enjoy. The trick is finding the right spot to set it up in, but once you have done that it is great fun and you get to see so much other stuff in the bush that you normally wouldn't see.
The worst part is being patient enough to sit in the thing until something comes a long.