I don't really think it does much other than maybe give a gentle shove if you're body is ready for labor to begin. So it may work or may not - no way of knowing.
I'm going to pass completely on it just because I don't want to risk ruptured membranes. Cause then I'm automatically stuck on the hospital clock and my body and baby just may not be ready yet.....and there I go in for another c/s if labor doesn't start and turn active within hours. Not to mention the increased infection risk. Awfully tempting.....maybe if I hit 41.5 weeks (right after Thanksgiving weekend) I'll be willing to attempt it if my MW is willing....after all my husband leaves later that week!