Strolling in to Waterstones on Friday morning to buy my copy of The Casual Vacancy, it occurred to me that I had not been inside a bookshop for years. In fact, I am pretty sure the last time I walked into a real, offline bookshop it was to buy Harry Potter and the Deathly Hallows in July 2007.

That is not to say I haven't read anything in the last half-decade. I like books, and besides, it turns out university lecturers really can tell if you rely on Sparknotes over Seneca for essay research.

But the world has changed. We have Kindles and iPads now. Even those who 'love the smell of new books' are more inclined to spend 50p on a second hand version from Amazon than £15 or more on a shiny new volume. Yet the numbers queuing in Waterstones suggest that another Rowling release inspires enough nostalgia to briefly put technology and stinginess to one side.

In the spirit of reminiscence, picking up 500 pages of The Casual Vacancy in Waterstones felt a bit like holding one of the heftier Harry Potter novels. Also familiar were the sheepish smiles customers exchanged at the checkout: we've all "grown up with Harry"; some of us probably queued in costume as children. The Casual Vacancy was always going to sell, but how well does it read?

The plot is a million miles from Harry's one-man mission to save the wizard world. It's set in Pagford, a "sleepy" fictional west country town, where the residents are nosy, gossiping and utterly self-involved. When Councillor Barry Fairbrother, possibly the only truly ethical character (though still a disappointment to his wife) dies of a brain aneurysm on page four, the race to fill his empty seat reveals a darker side to life in a small town.

A lot of critics have waxed lyrical about the various political agendas in Rowling's latest work. Perhaps I'm as small-minded and ignorant as a Pagfordian but pondering whether the book is "500 pages of relentless socialist manifesto" (the Daily Mail) or "a force for social good" (the Times) was not what kept me reading.

Rowling's skill lies in her depiction of people: real people who are lovable and despicable, funny and tragic, and sometimes all of those things at once. This was true for the Potter novels, and it is just as true now. The Pagfordians are horribly human. Rowling offers such intimate access to their minds that at times it is almost disconcerting. Candid descriptions of Samantha Mollieson's jealousy over the sympathy accorded to Barry Fairbrother's widow and the morbid fascination provoked by his funeral make the reader question their own morality. Rowling articulates in black and white those nagging, evil little thoughts that most of us are pretty successful at hiding.

However, when the characters become too extreme, too evil, her magic formula starts to falter. The hideous rage and stupidity that made Vernon Dursley so entertaining becomes ludicrous in Simon Price, a small-time criminal and full-time wife beater. Another let-down is Krystal Weedon, the daughter of a "junkie prozzie". Her grim home life might be well researched but her mannerisms and dialogue seem crudely stereotypical.

Potter fans will appreciate Rowling's efforts not to superimpose Potter characters into a decidedly Muggle world. It is almost impossible to identify any traces of the Hogwarts crew in Pagford, not least because of the adult themes and language.

My main problem was that while the people were plausible, their fates were not. Perhaps after spending so many years on a series that worked meticulously towards a grand finale, Rowling got bored with writing stories. The Casual Vacancy is not so much a tale as it is a snapshot, analysing and exploring the drives and desires of characters who, unlike Harry, have no vocation. Their thoughts and actions are realistically selfish and while this is discomfiting, page-turning is driven by the same mildly mawkish, passive interest the Pagfordians display at Fairbrother's funeral. Melodramatic deaths that worked in the context of a magical battle appeared gratuitously miserable – more grown-up Jacqueline Wilson than JK Rowling.

No one would wish to escape to the "world of Pagford" and there is no real scope for a sequel, making it hard to see how the book could ever enjoy even a fraction of the success of the Potter series. One gets the impression JK Rowling is now writing for herself, rather than her audience and, after seven Harry novels and eight films, I say: fair enough.