The blinds work. It's just that simple.
You can go hunting wearing a pink ballerina's outfit (if that were your thing) and still be invisible to the animals when inside the blind. The turkeys look at it as if were just another bush and I've had deer walk by downwind of me and show absolutely no reaction. It allows you to move around and strech your legs without worrying about spooking game you did not see. Your scent is contained even if it's not carbon lined. They are also very quick to put up where a pernament blind simply won't go.
I'd still make an attempt to blend it in to the local surroundings. Even if it does leak a bit of water during a heavy downpour it's a heck of a lot better than getting soaked if you weren't in it at all.