There was a point, when I was flicking through this book prior to reading with concentration, when I asked myself: "Is this really meant for me?" The size of knickers you should wear, the decision to depilate the pudenda or not, and the question of heels, I thought, are unlikely ever to be problems that are going to bother me in a real sense. I also wondered whether I should be reading this book at all; as if by doing so I had sneaked into the ladies' loo, hidden inside a cubicle and overheard a conversation that was not meant for me. Chapter headings: "I Start Bleeding!" "I Become Furry!" "I Need a Bra!" "I Encounter Some Sexism!", and so on. These are not my things, although I once encountered some sexism when a woman left me and a male friend with the words: "I'll let you get on with talking about tits or whatever it is you talk about when we're not around."

I'm still a bit cross about that, actually, for like all male Guardian readers, I like to think of myself as someone entirely sympathetic to the whole feminist project, as long as it doesn't involve too much shouting at men. Or what happens when you leave the politics out of it, creating what Jenny Turner described as "a weird sinkhole that quickly filled up with the most dreadful rubbish: wise wounds, herstory, nature goddesses, raped and defiled; sisters under the skin, flayed and joined, like the Human Centipede, in a single biomass; the fractal spread of male sexual violence, men fuck women replicated at every level of interaction, as through a stick of rock."

Anyway, I sat down and started reading How to Be a Woman properly, and by the time Moran says "in many ways, there is no crueller or more inappropriate present to give a child than oestrogen and a big pair of tits. Had anyone asked me ... I think I would have requested a book token or maybe a voucher for C&A instead", I realised I was in the company of someone who was going to keep me amused and that, frankly, is the bottom line. "I'm neither 'pro-women' nor 'anti-men'. I'm just 'Thumbs up for the six billion.'"

I had never come across Caitlin Moran before: she writes for the Times, which perhaps accounts for the lack of politics in the book. This absence is very much a dog not barking in the night; I wonder whether it was a deliberate decision not to alienate her readership, or genuine indifference. Not that there is any dreadful rubbish in here: it is, quite simply, a book that might as well have been subtitled "common sense, with some very good jokes".

It is as a comic writer that Moran particularly excels; by which I mean that the jokes aren't gags sprinkled around to make up for the surrounding pieties, they are integral to the whole project. Her account of the birth of her first child is absolutely mind-boggling and nerve-racking (and, while we're on present participles, breathtaking, in terms of the quality of prose used to describe the pain); and her very lovely-sounding husband's agony at her suffering is beautifully and memorably described. But then she can still squeeze in a good joke on how the whole experience has given her perspective: "I doubt that I will get angry about Norwich Union changing its name to 'Aviva' ever again.'" (There are no jokes in the chapter on abortion, though; but it is still level-headed and honest.)

I presume that every woman who can read anything more challenging than Heat magazine has bought this book; good. Those who do read Heat and little else should also read it: it's healthier, and Moran's description of Katie Price's nasty self-absorption strips all the cant away from assertions that she is, somehow, a feminist icon. But pointing at folly and laughing at it, whether it is spending £21,000 on a wedding or having your expressions Botoxed away from your face, is a superb technique. The clever bit will be to get men to read it, too, so that they can finally answer the question that bothered Freud so: "What do women want?" To which the answer would apparently be: "Pretty much the same as everyone."

Before we start, let's be clear: this is a great big hoot of a book. There are lines in it that will make you snort with laughter, situations so true to life that you will howl in recognition. It is very, very funny. So, you could read it just for that, for the entertainment value.

However, if you are female, and particularly if you are a female under 30, then, tucked around the jokes, Moran has provided you with a short, sharp, feminist manifesto. It's not academic: she doesn't present a research paper into gender differences in pay or interview women who have suffered domestic abuse. Instead, she uses her own life to examine the everyday niggles of everyday womanhood  hair removal, getting fat, tiny pants, expensive handbags  as well as the big stuff such as work, marriage and kids. She pins each topic out like a live, wriggling, sexist frog, ready for dissection. But, instead of scalpelling it into little bits, as, say, Germaine Greer would, Moran tickles it so hard that the frog has to beg for mercy and hop off.

Moran, a columnist for the Times, writes very quickly, so How To Be A Woman is timely. (In fact, if you're a regular reader of her columns, you'll be familiar with some of the book's topics  her wedding, the joy of bras, meeting Lady Gaga.) The book is also on point: like the best columnists, much of what she says is something you've already thought of, but not articulated, not quite. And, like I say, it's funny. Humour is, of course, the coolest, sharpest weapon in humanity's social armoury, and it's one that feminists, supposedly, lack. (Though we might mention Tina Fey, Joan Rivers, Nora Ephron)

So, perhaps, the very fact that How To Be A Woman is so hilarious is its greatest strength. However, the parts of this book that I loved the most were actually the most serious. There are moments when Moran writes about her unconfident younger self that make you want to clutch that small person to you and say, "It will be all right". And her account of giving birth and  particularly  of her abortion are exceptionally moving. Not because they are feminist. But because they are true.

The book's structure loosely follows Moran's life, from child to thirtysomething, with the feminist analysis woven in between. If you wanted to be picky, there are a few occasions when this analysis doesn't quite work. Her conclusion about pornography is pretty woolly.

There are times when her test for sexism  equating it with a lack of politeness  will not work. But, for this reader at least, that is made up for by her seven-page rant about the delight of pubic hair that includes this observation: "Lying on a hammock, gently finger-combing your Wookie whilst staring up at the sky is one of the great pleasures of adulthood."

And Moran's final, simple argument, that there should be more of us, more, different women taking up more space and having more power in the world, is spot on. Why should women only be allowed to be seen and, particularly, heard if they are deemed acceptable enough to do so? Acceptable meaning "pretty and of the right age". You only need to go online, to read the blogs and tweets of the thousands of anonymous women out there to realise that we have as much to say, and can say it as cleverly and wittily, or as irritatingly and crassly, as men.

Moran has written for the Times since she was 17. She has won awards for her criticism and interviews. She is not an "ordinary" woman by any stretch of the imagination. However, the very nature of being female in the UK means that you share the same life architecture as most other women. Your life is structured in much the same way: to be blunt, you are sold the same shite. Brazilians, Botox, babies before you're too old: even if you know that you want none of these things, it can be hard not to be affected by an overbearing general atmosphere that tells you that you do. You must.

It can be hard not to be cowed.

The joy of this book is just that: the joy. What Moran is really arguing for is more female happiness. Women spend too much of their time worrying, beating themselves up, going along with time-wasting, restrictive, often expensive, sexist mores. The triumph of How To Be A Woman is that it adds to women's confidence. It reminds us that sexism, and all that is associated with it, is not only repressive, it is tedious and stupid. It is boring. Best give it a body swerve and get on with having fun.