I recently bought an older edition. First I'll say, while i understand the one star and two star reviews, -- the point they seem to be making is that swotting is not the same as learning -- I think this book is a worthwhile purchase, and owning it will do no harm to anyone, even if you hardly use it. However, considering it a 'passport to high grades' or 'vital to A level/ University level French' might be a very bad idea, as other things to be far more important.
I can speak from experience: I did my A level around ten years ago and got 267/300, without resits. I didn't revise, or hardly, -- not because I was lazy, but because I couldn't see the point. I worked reasonably hard, and above all, I enyojed the course. I certainly didn't 'swot' with a book like this, or with any other vocab lists. (I didn't own any textbooks or reference books apart from a dictionary, and didn't use any books apart from the one class book and the photocopies that were handed out in class.)
My feeling is, that for some A-level students, repeating sophisticated phrases that they memorise from a book like this will help them feel serious and professional and give them confidence. Yet it probably would have had the opposite effect for me: the idea that the phrases I naturally produce are not good enough would make me feel less confident, and if I felt that I would be better off parroting phrases from a book, it would break my flow, and would make me find it hard to take the course seriously, the whole thing would feel more like a pointless game.
Here is some general advice from a languages graduate, it tells you what I mean when I say 'swotting' is not the same as learning; some of you will know all this, but for those who don't: independently doing listening exercises (not just for comprehension but for grammar, vocab etc), reading a newspaper or listening to the radio are stimulating activites which make you think for yourself, allow you to make your own observations about how French language works, and gradually get a feel for the language. Jump in the deep end, get a student-price subcription to le Nouvel Obs. (And use Mot a mot as a handly lexicon while you read). At university level, 'swotting,' or Over-Relying on a book like this, will not cover up the fact that a student has not done this work, just like sprinkling icing sugar on a chocolate cake will not hide the fact that the cake is not very good.
At university, the most important thing is to know the basics well. You get heavily penalised for making numerous basic errors. You get a mark for your basic level, so using a very obscure grammatical structure eg the imperfect subjunctive correctly will probably not boost your grade, not even slightly, nor will very sophisticated vocab. For more information about how to use the your study time effectively at Univerity, in a way that will boost your grades, consider looking at a book like ''Study Skills for Language Students: A Practical Guide'', and ask your tutors etc.