The Battlerager Fighter build is absurdly powerful. Here's a suggestion to bring it on par with other weapon talents, while preserving as much of the original mechanics as possible.
Replace the Battlerager Vigor Fighter talent with the following:
When wearing light armor or chainmail, you gain a +2 bonus to damage rolls against enemies that have hit you with melee or close attacks since your last turn. Increase this bonus to +3 at 11th level and +4 at 21st level
This is a refinement of an idea I proposed a while back at the wizards.com forums. Essentially, by adding the requirement of hitting an enemy, the amount of THP gained is halved. Also, it no longer activates multiple times when several enemies attack at once, so Battleragers can now be overwhelmed by superior numbers. More importantly, the dreaded minion immunity is gone for good.
Given this sudden drop in power, you might think that this new version is now too weak. Far from it. Characters with good Constitution will still gain lots of THP, it's just that now they just mitigate enemy attacks rather than almost negating them. The combination with Invigorating can also be effective, as well as spectacular: it's not difficult to have Invigorating, Battleraging hits that heal for double digits. Of course, this isn't any more than what previous stacking rules allowed, but gaining the THP in single bursts should feel impressive, anyway.
Putting aside balance concerns, I like to think that the revised mechanics should be more fun in play, too. The need to hit makes character building more interesting,since the build with the best defenses is not necessarily the one with the highest Constitution. Also, there are now stronger reasons to go with the recommended weapons and armor, although other choices are definitely viable. Finally, the need to go for the guy that hit you provides the raging flavor that was sometimes missing in previous implementations.
But the best of all is that, no matter how good these battleragers turn out to be, their desperate need to hit means they will always miss the Weapon Talent they had to give up!