A bit skeptical of this when I ordered it, I've since come to rely on it. Not only a great way good to stretch out before practice or a round; when used properly, it's helped to fine tune my tempo, timing, swing path and release.
Practice 5-10 minutes a day and you'll notice the difference.
Just a few minutes while waiting at the first tee eases those first tee jitters. My swing is smooth and seems almost effortless.
Just one caveat: I wouldn't recommend this to those with back problems. At least, get one of the lighter models.