They have been on for about 15,000k's now and haven't worn too badly. That's probably because I don't go racing around corners all the time.
They are quite noisy for my car. I've gotten used to it, and it has actually quitened down since they were first put on. The noise is almost comparable to a wheel bearing gone, but much quieter.
They do more than what I need them for, but atleast I now feel safe in the wet in my Pole Magnet.