This skill is great, how ever I don't think I will pick it up. Don't get me wrong it is linked to 6% more D, with Blade Barricade and is off GCD so anytime (every 6 sec) you can let them have it. That 6 sec is my first reason I will not be picking this up, why you don't plan on using this skill before or after a said skill, you will use it when you can. You want to use it 100% of the time, but b/c you don't plane to use it, you will let it go to pop off a AOE or a Leap/Intercede to get arggo or be a Tank. 6% D is epic but is not a must right that sec, sometimes you will have to let this go 8 even 10 sec for reasons of pure chaos. This 6% D is best at the start of the fight, when you have ex skills that give you rage.
No less a great skill, just don't think it is a must have, a must think about non the less.
I really like this ability. I believe it has good symmetry with the play style of the immortal jugg, and with the Blade Barricade Talent (http://www.torhead.com/ability/9vCdHcw).
It allows you to freely use the Retaliation ability only costing 1 rage. The ability is off of the GCD, and can be dropped in anywhere. With Blade Barricade the Defense bonus makes this extremely useful, and a must in tank builds.