First off, the Shard is an abomination, and it should not be your lead image if you want us to like London more. The first clue is that it is called the "Shard." The second clue is that it looks like aliens decided to mine the rich veins of bad teeth found under London and dropped some equipment from space to do so. In fact, I hope it is merely scenery for an incredibly high-budget special episode of Doctor Who. The excrescence's only redeeming feature is that it is so far out of scale that one can tell that it's on purpose, though that is small consolation for bollixing up the entire Metropolis.
Second, we know that London is great. We do not need a defensive and condescending special report to tell us so, especially from the last mouthpiece of Empire (however reasonable it generally is). I'll wager that absolutely no one who reads The Economist is unaware of London's assets--and very few of them are ignorant of her drawbacks. The ungrateful knuckle-draggers in the midlands or wherever at whom the whinging is directed are not among the readership.
This is gross, pointless, and partial journalism, if one can even call it journalism. Get back to your surreal obituaries of Ray Bradbury, chaps. (Although, seriously, what the hell was that?)