Jemima Lewis: You would have to be a fool to flee London

London is under attack. Not physically (not yet), but in the pages of the national press and around the dinner tables of the chattering classes. The question of whether our capital city is fit to host the Olympics has brought the doom-sayers out en masse. London, they gloomily intone, can hardly function as it is, let alone with an extra nine million sports fans clogging up the works. The Tube is falling apart, Ken Livingstone's congestion charges are going to paralyse the city, crime and squalor are spreading like cancers.

Of course, Londoners have a long and enjoyable tradition of slagging off their home town. Samuel Johnson – whose affection for the city was beyond question – called it "the needy villain's general home, the common sewer of Paris and Rome". But the current London-baiting seems to me peculiarly misplaced. Far from going to the dogs, London is better than ever. Once famous for its filthy food, stinking air, blackened buildings and atmosphere of defeat, it is now a neon-lit and cosmopolitan place of beauty.

If you doubt me, walk across Waterloo Bridge at night. The banks of the Thames – for so long dark and neglected – are now ablaze with light. The futuristic pods of the London Eye, the golden silhouette of the Houses of Parliament, the glowing red sign of the Oxo tower, the blinking lights of far-off skyscrapers, and the pale, silvery dome of St Paul's: London, which always lacked a proper nocturnal skyline, now has one of the most ravishing in the world.

How this came about is – like so much in the capital – a mystery. Historically, Londoners have been too busy making money to pay much attention to the way the city looks. There's no central authority – unless you count Ken, and most people don't – to take charge of titivating the place, and yet somehow, miraculously, it is being done.

New treats have popped up through a combination of private and public enterprise: Tate Modern, the Eye, the ice rink at Somerset House, the immaculately reconstructed Globe theatre. Two splendid new footbridges across the Thames (the Millennium Bridge and the revamped Hungerford Bridge) have made it possible to amble around these places without ever encountering a car. Londoners finally have a place to promenade.

Of course, central London is only a tiny part of the whole, the jam in the doughnut. Most of us live in the doughy part: the vast stretches of Victorian and 1930s terraces that circle the city. These are not, on the whole, places of beauty. Our high streets have become uglier in the past half-century, blighted by plastic shop fronts, swirling litter and yellow police boards advertising the latest rapes and murders. Yet behind the scenes, even these unprepossessing areas are being slowly gentrified. Only 30 years ago, let's not forget, most of Notting Hill was a slum. Today, it's a pastel-painted sanctuary for international fashion victims.

Not everything is perfect, I admit. Gun crime, graffiti and the stench of fast food detritus are all relatively new horrors. London still boasts some of the world's most incompetent town planners and architects. Greedy developers prowl the city, itching to tear down anything of beauty or interest (Spitalfields Market being a case in point) to replace it with another banal office block. In place of slums, we have high-rise sink estates. The Tube is getting grottier and less reliable, and the road-work situation is out of control.

But these are trifling complaints. Fifty years ago, it was a parochial city of bad food and gloomy attitudes, its beauty destroyed by the Blitz, its spirit broken by the end of the Empire. Now, it has become a city of pleasure. Londoners eat better – and more adventurously – than anyone else in Britain. My local high street alone boasts a Portugese bakery, a Brazilian supermarket, several Caribbean takeaways, a modern British gastro-pub and a Lebanese greengrocer. Culturally, too, Londoners have become more daring. Last summer the people of Hackney gathered in their thousands to see the Royal Opera House's performance of Romeo and Juliet beamed on to a screen in Hackney Marshes. Outdoor film screenings in Clapham Common and Victoria Park have become part of the summer season, like long, hot days at the lido and Shakespeare in Regent's Park. Every evening after work, thousands of grey commuters tear off their suits and gyrate wildly at salsa clubs and belly-dancing classes. We've come a long way since the demise of the bowler hat.

And this is just the beginning. Those faithless Londoners who are now fleeing the city in droves, heading north in search of cheaper housing and a better "quality of life", will soon be kicking themselves. Only a fool would willingly surrender his shoebox in the greatest cityon earth. As the American thinker Robert Dahl said: "If to live in cities is our fate, to live in great cities is our opportunity."

Jemima Lewis is editor of 'The Week'