Well...I don't have the 'full' Passporter book, just the tips book that is an online download. It is full of lots of reader tips collected the past few years.
This may be my second cruise, but I found it very informative about packing light, ways to save money, things to do on the cruise (I hadn't thought about before).
I think the DIS board has a lot of the same info, I just didn't know about the DIS board before I ordered the book. But it is a nice little reference.