Yes, I have been using them for about 6 years.
The best is the spikey platic one, the worst is the metal one that looks like a flap over the muzzle.
Hardly any method involved putting it in. Head in headgate, loosen the wingnut put ring in and tighten wingnut. For removing put head in headgate loosen wingnut and pull out. Sometimes the ring grows through the septum and you end up with both knobs in the same nostril. From experience its better to push both through the septum to the other nostril and remove one knob and then the other pulling it back through the septum again.
It helps if you can start the calves on feed before weaning if your pasture isn't great, put rings in and leave them with the cows for about a week, then you can remove the calves if you want, but keep the rings in for now incase some cow decide to come fetch the calf.
Success rate is about 95% for me, long teats and first calvers that refuse to wean the calf can sometimes cause problems, but overall a great invention. They last a long time, but you'll probably break a few each year when removing them.