I think the big change comes from now you can still do your barbarian's damage while you are under the fury but now add a multitude of small affects while removing the small hindering parts.
Example: *Devastating strike at-will [1W] + 1d8 + [STR] effect take a -2 to AC until start of your next turn. The alternative is that while you are under fury you can now choose to either do shift 2 squares before the attack, slow the target after the attack or make the target grant combat advantage without taking a -2 AC unless that's the effect you wanted to go for.
Also if there are any previous rages that cite it does extra damage for primal attacks or anything like that going into the fury grants all the martial powers the keyword of Primal so you'd still have those effects tied to them.
Another thing, looking at the book it does not seem that berserk takes the place of rageblood or thaneborn or any alternatives in Primal powers so you can keep your damage up without taking -2 AC and still rage/get bonuses from feral might.