The good and bad points of London (or any other big city) are always two sides of the same coin.
It's the fact that there are so many people crammed into the city that create the traffic and litter problems we all bemoan. But it's that same concentration of people who make possible the city's vibrant arts life: not just the West End, but dozens of tiny little pub theatres doing good work too; not just the South Bank, but hundreds of live music venues offering every genre under the sun; not just the multiplex, but every neighbourhood's thriving independent cinema offering imaginative programmes of their own; not just the heritage architecture we all admire, but exciting and innovative new skyscrapres too; Not just the HMV megastore, but dozens of tiny specialist record shops energetically pushing their own enthusisams.
London's crime, rubbish and traffic problems are the price we pay for the astonishing vitality this city has to offer. New York is London's only real competitor, and there the move towards making it a safer and more controlled city has also made it a far duller one. If you can show me a place to live that has the gentle ambiance of country life, AND the cultural vibrancy of London, I'd move there tomorrow, but you can't have the good stuff without the bad.