I'm not sure there's anything wrong with before_filters. They're awfully useful, and have never gotten me into trouble before.

I don't think the argument is that filters are bad, but the fact that they are often qualified with the :only or :except conditions is a sign that they could be better.

Going this far away from Rails conventions makes your code less understandable for future maintainers, and potentially takes on some risk of the gem not being supported in future rails versions.

Since the author is a rails-core developer, I think the idea is to try this out as an experiment and see if it makes sense to change how Rails itself works.