Originally Posted by
Archimtiros
Actually we were unsure. When said a long attack like that didn't feel very "furious" and asked if it worked like Fists of Fury, WCD said it wouldn't be a channel and you could continue to take action during it, which implied it worked like Flurry of Xuen (MoP DPS Cloak), that is to say you would be able to use other abilities during the "flurry". Turns out you cannot, though you can use Heroic Strike and other off-GCD abilities.
This actually has pretty huge implications, because without Carnage it's not a very good attack to begin with. It does good damage, but the long GCD and the high rage cost make it very inefficient compared to Raging Blow. Since there's no charge system on Raging Blow, preliminary line of thought is that it will be an un-enraged or rage dump only ability unless using Carnage.
Also, updated the OP with a key note.