This looks pretty interesting and I have thought about getting it...but your remark/review confuses me a bit. Do you actually own it, and have you performed it? Are you stating your opinion solely based on reactions on the demo?
I own "Deuce Bag," which is now known as Witness. So, I'm a tad confused as well -- do I own Witness or do I own Deuce Bag.
All joking aside, I have performed the effect. I love Witness and/or Deuce Bag for its simplicity, but also for the hard-hitting reactions that are garnered.
When I said "just watch the preview," I meant don't take my word for it. Moreover, feel free to check out some reviews, like this one --
http://forums.theory11.com/showthread.php?t=2130.
Hope this clears it up.
Cheers,
JTM