Quoting MMO Champ news article from today:
While the prot ones don't really produce any "wow" effect and seem rather unreliable, the dps ones are interesting.•Item - Warrior T15 DPS 2P Bonus (New) Your melee auto attacks have a chance to trigger Enrage.
•Item - Warrior T15 DPS 4P Bonus (New) Activating Skull Banner now also increases your critical strike chance by 35% for 10 sec.
•Item - Warrior T15 Protection 2P Bonus (New) Your Shield Slam and Revenge have a 10% chance to activate Victory Rush and increase the healing done by the next Impending Victory by 100%.
•Item - Warrior T15 Protection 4P Bonus (New) Your abilities generate 50% more Rage when used against targets afflicted by Demoralizing Shout.
The 2p bonus seems very strong at least for fury (depending on proc chance of course), assuming it triggers a normal enrage with all its effects including rage gain, rb proc etc. There will naturally be some unreliable overlap with rb procs and enrages from other sources. The 4p on the other hand affects our cooldown stacking quite a lot and seems to require some math to determine where and how it's going to fit in the bursts compared to reck due to the fact that both can obviously no longer be used simultaneously if you have this 4p.