fitted some to my 'hack' bike as they were the cheapest thing I could find.
now running them pretty much all the time, don't have to worry about gritty shitty cables and hoping the clickety click will actually make it to the next sprocket.
cheap, light, functional.
Sure, it's a bit slower to shift, but in reality I can now spend more time riding my bike than swearing at it.
(ok, well I would if I wasn't at work)