The moment I realised how overpowered Revenge is was when I first saw it proc'd from ranged attacks / spells. I had always assumed for balance it was a melee only skill.
I don't generally play melee characters in games as I don't like being picked off from ranged enemies. I see this as a great way to counter that sort of incoming damage.
example : You're surrounded by mid level melee mobs taking hard spell damage over the top from a group of ranged casters - no problem snuggle up to those mobs and you're getting through them quicker and healing yourself. Win -Win
Provocation is the obviously overpowered rune choice, I can see it getting toned down a bit in the first few weeks of live if not before. I would use this skill in any and all Barb builds.