First things first. Why the Hell was this book called the Cup of Death? I could've sworn the book I read was about some tea bowl. Anyway, interactivity to me, is the effect on a user's actions on the outcomes of an event. However, the honest fact is, that in this book, my actions really do not effect the outcomes at all. They are already written down, and even though I may be able to choose different page numbers, I do not feel like I am really interacting with the book. Besides, if I happen to choose the cab ride that gets hit by a car, I can just flip back and pick the other option. Overall... pointless.
Interactivity should be more in depth then picking pre-determined ways to die, or ways to catch a thief. My actions should create its own set of unique outcomes, and not just a different combination of the same ones that everybody else can choose as well. I do understand that these books are intended for a much younger audience, and that being able to pick what the character can do may make reading more enjoyable. Kids like hands on activities and the choose your own adventure series makes reading a little more hands on.
True interactivity may be impossible to create in any book or video game. It can't be possible to create infinite possibilities in a book, and in the case of Zork and similar video games this is true as well. Although Zork and other games can program many more possible combinations that a user can go through. I believe that technology is getting close, especially with games like the Sims, where basically you can create a second life for yourself, to creating an interactive environment, but I can't give the nod to The Cup of Death to be considered interactive.