From a practical perspective of someone who lives and works in London, it's already a nightmare.
But hey, there are only 8 million people living in London and probably only half of them are going to be affected by road closures, diversions, parking restrictions, traffic jams, clogged trains/tube/buses. And about 40 times that many will be watching around the world. So the needs of the many outweigh the needs of the few, right.
As for me, I'm not fussed much about sport really so I'm getting out of the way and leaving the area. I'll watch some of the opening ceremony, perhaps some tennis and maybe I can spare 10 seconds for the 100m sprint.
I agree about sport though, the Olympics is a great promotion of sports to the youth of Britain. Even if only 5% of the slackers get of their bum because of it, then it's good.
Sport is one way for kids to be inspired, fulfilled and find something they are good at, which is good no only for them but for those around them.
I used to play tennis and cycle when I was a teenager and along with music, that kept me plenty busy and out of trouble.