I own both versions of this effect: the one with the smaller booklet (which is pocket sized), and the new, improved one with the slightly larger book. For an educated audience this is a great effect. Are you a math teacher? Then yes, you need this trick. I’ve performed it a few times, and it always impresses the spectator(s).
The “downside,” if you want to call it that: you need to know your stack VERY well — unless you buy the stackless version. How well? Well…well enough that you can quickly perform some mental arithmetic while reciting your stack values in a hurry. I ended up memorizing the mathematically altered values separately just so that I could say them faster and recall them more spontaneously. But that’s more memory work. So in other words, this is the kind of effect you want to perform or at least practice very frequently if you plan to do it. Because if you plan to just do it occasionally, the memory content won’t be there for you. Even if you’re very conversant with your stack (as I am with Aronson’s), you’ll still be doing some cognitive gymnastics during the performance.
Hence, while I recommend this effect without reservation, I would just add that you’ll need to work on it frequently to keep it fresh — more so than you would other effects in your repertoire. Further, make sure you connect pi to the human element: discuss how each person’s life history is written in pi, etc. Otherwise, the presentation could come across as dry and self-serving. It’s important to transform a potentially “look how smart I am” effect into one that communicates “isn’t this fascinating for all of us?”