Some of the rules are sensible: work hard, do more than asked, be diplomatic and nice with everyone. Others are like: dress smart and expensive clothing/accessories, learn to talk like the bosses, learn to walk like them (yes, he says even that), be friendly with the "herd" but don't go to holidays with your colleagues, remain cool, avoid office parties, donate for the red nose day, but don't make a fool of yourself by wearing one of those red noses (yes, it says that at some point). All is told in that crap style typical of self-help manuals or motivational quacks. All is exemplified by means of anecdotes, which are supposed to come from the author's personal experience, but which are evidently and annoyingly invented (none can possibly have happened such a variety of things and have moved through so many jobs).
My interpretation: if you want a successful career in a boring, formal working environment, were everybody wears the same sad suit and it's all about form, power, hierarchy, employee cuts and profits, read this book. If you happen already to be in such an environment and even like it, you have all my sympathy, read this book (better, just have a look while you wander at the bookshop, it isn't so worth a purchase) and maybe you'll realise that you don't want a successful career as a slave-in-suit after all.
I personally was initially curious, but no, not for me. I have always aimed at a different type of job, I don't need smart dress code, to prepare the coffee for the boss and all that rubbish. I like to do my job seriously, but also to wear the red nose, without fear to be judged a fool, for my bosses do it too. I can see that business people like Steve Jobs or Mark Zuckerberg probably don't even own a suit and I suspect ever more businesses are becoming ever more informal and more concrete, even in UK.
Trouble is that most of jobs, whatever the form, are still authoritarian and most businesses, whatever their crap about mission statement or HR slogans, still care little about individuals, participation, opinions, feelings and desires. You can get a glance of what this means by reading this book (well, no, giving a look while in the bookshop is enough). But if you read "The Dilbert Principle", you'll get it even more and certainly you'll have more fun.