I was just in Amsterdam recently and hired a similar thing (Mac Bike, I think it's called). Very quickly got used to the city's transport system, and had no problems at all. I'd be wary of a visitor coming to London and thinking it's going to be as easy, though. You have to be much more assertive here, and there's a limit to how assertive you can be on a bike that weighs about 5 times what a fixed weighs. But then again, Paris traffic is similar to London and it seems to work there.
I was just in Amsterdam recently and hired a similar thing (Mac Bike, I think it's called). Very quickly got used to the city's transport system, and had no problems at all. I'd be wary of a visitor coming to London and thinking it's going to be as easy, though. You have to be much more assertive here, and there's a limit to how assertive you can be on a bike that weighs about 5 times what a fixed weighs. But then again, Paris traffic is similar to London and it seems to work there.