Hey, Dat -
I know you asked Katrie, but I thought I'd offer my two cents.
It's a great effect. I was actually surprised. I initially figured this purchase would be geared more towards younger spectators, but was happy to find that EVERYONE reacts strongly to the effect.
Also, it should be noted to all, that you can purchase a new set of presto printo cards directly from Daryl's site
http://www.foolerdoolers.com/store/default.asp, so the effect can be repeated.
It's definitely worth the purchase. Personally, I'd find an older version (the newest one comes with a dvd, but is more expensive) - work out the handling, and adapt the trick to your style. you save yourself almost half the price and the effect is still killer.