yup, they work great!

Take some 2x4s (P.T. if you got some), and cut em to a point at one end, drive em in as4 corner posts. Depending on your size you maywantone in the middle,then take some wire and make a mesh to put brush in. You could use plywood, but why bother. I keep some old carpet in the barn cut in squares to lay in the bottom. Just make sure you can shoot through the brush easy enough. Play around w/ it you'll get some nice setups.

Sometimes it helps to dig a pit first, bout 2' deep. It helps for many reasons, keeps you cool in the early season, helps keep your scent in, gives you a nice clean bottom, and makes it easier to conceal.

If you wanted to go all out you could make a box.. but thats a lot of work, and $$... this method is less permanent too.