I've used one of these blinds for the last 2 or 3 years, and just bought a Final Approach layout about a2 months ago.Theshell blindsdo work ok and you can shoot geese from them..but..
It's defintaly a hassle keeping your shin/foot area covered up, you always need to have a little something to break up the outline of your legs, and like GWN3D said, they are akward to get in/out of. It's a little uncomfortable sitting when your waiting for the birds, and a little hard to see the birds as they're working. Although they have there disadvantages, they do still work.