It's true. This book not only tells you like it is, but preety much tells you the way you need to "act" come the assesment centre day..
From the begining the author (who is a former inspector) lays out the ground rules, why he doesn't paticuarly like the current system but at the same time reminding you that if you want to do the job. Tough.
The book goes from application form right through the assesment centre. As well as the core competencies that you will be marked on.
Further to that, the book goes in depth in how you can get the top marks in each competencie, like a checklist if you will and this relates as well to the interview and role plays.
Although not telling you exactly what "questions you will get on the day" in the interview or role play, it does give scenarios and what to expect and I would imagine, come assesment day, they aren't far off the mark. You can then get you and a friend to mark you and then remind yourself for next time when it's the real thing!
I think this is the best book by far for those who are about to attend the assesment centre. It's up to date (released 2010)and I believe sets you in good steed for what to expect.