I use them! 2 nipples in a 5 gallon bucket, one bucket keeps 10 chickens watered for 5-7 days. I do provide water in an open source bowl for my turkey in the really hot water. It takes her a lot longer to drink because she can only get so much from the chicken sized nipples. Didn't have any issue at all converting the flock. I demonstrated with my finger and when they saw it drip they caught on. Anyone who didn't see me, saw other chickens doing it and learned fast.
The only leaking issue I ever had was accidentally drilling at a slight angle. I put silicone around the opening after I screwed the nipple in and let it dry and that fixed the problem.
I have used the Avian AquaMiser type and some from eBay (the kind you can take apart). Both have worked excellently.
My first chickens ever I trained to drink from a hamster bottle as chicks so watering the flock when they got older only made sense this way after I discovered it was a real thing.