London buses are really not something you want to try to use. I spent a couple of years working in Chelsea, which was deliberately omitted from the tube system (the rich inhabitants did not want the great unwashed to have an easy way to get there, I suspect). So walking or bus, or if you had more money than I had at the time, taxi was the only option. Walking was far faster than any bus.
Blame Boris for cancelling the extension of the congestion charge to west London. Through central London they're not too bad anymore, at least that was my impression living in London a few years back.
I'd say it was very good compared to just about any country that is not in North Europe. And I really don't have an issue with busses anymore in London. TFL have a fantastic API which tells you when the bus you want is arriving at a stop amoungst many other things.
