I've heard they are very delicate, don't acclimate well to captivity, and generally are hard to keep.
I've also heard personal anecdotes like Keith's about people keeping them easily.
I think there are more than one species of ringneck snake, so that might explain the different reviews.
I have some friends who live out in the country and find them in their pool all the time. They are adorable and I'd love to try keeping one if I knew more about them.
i know people who kept them successfully to the point of breeding, i have had such luck myself. i let them go by our family cabin, near a creek. i have seen them breed in the wild. they were picky eaters back then too. crickets and redworms mostly...good luck!