Is any place "guaranteeing" a 100? If not, it sounds like this person being overly critical for no reason. Next time study the book for a few weeks and let us know how it goes
I had a good experience myself recently at ATP in Phoenix/IWA. From what I understand, there are usually a couple of questions that change slightly from time to time, and they supposedly update the bank frequently. I saw perhaps 2 questions that were not on the prep, but were either common sense or a little different than the prep. I also had a friend get a 100 there with no pre-study and a few hours with the software. Seriously, the fact that you can study for only a few hours, take a test for 30 minutes, and walk out with a high 90 was good enough for me.