After hitting 70 and running few instances for a past few days on WAR I must say that whoever design WAR for SB has some kind of schizophrenia.

They want us to stay in tanking stance for as long as possible, they discourage us to switch between stances (WARs especially) and yet, the cheery on the pie of this expansion for WAR is ability that benefits WAR in non-tanking stance only...
I just don't understand it...
About Onslaught everything has been said. Without revamping it, it will become obscure.
Shake it Off is meaningless, it could be nice (albeit a bit OP) if you were able to remove debuffs that healers cannot. We should have some circular AoE here, which lack of really hurts now, especially on pulls, especially that we lost Flash.
Upheaval is nice, I'm frankly quite suprised how good numbers you can pull from it. With full HP it has higher potency than Inner Beast, buffed can hit over 15k on ilvl 300 Warrior. It's nice addition to our tool, but the problem is that it is viable only in Defiance and the time window is really really short considering you have to hit with it when you have full HP (it scales down really bad)...
Enhanced Infuriate is also nice addition, it helps us get necessary tool (either IB for defense or SC for enmity) sooner... But again, it messes up with Berserk timers.

I also found some issues with enmity. For me it, looks like you don't really need BB combo anymore for single targets, but at the same time both Overpower and Steel Cyclone enmity generation is somehow lacking. But maybe it's just me and I need to adjust to new reality.

I think that SE went in completely wrong direction with WAR. They want us to tank, but gave us not a single real new tool to do that, not a single incentive to stay in tank stance. They just force us to stay in it by removing some of our tool set and nerfing attack power algorithm. I don't like it.

But I like Beast Gauge. Really like. Basically, you are now not limited to 5 stack but to 10, it gives you much freedom. You can Steel Cyclone a lot more, which without any other circular AoE is priceless. Reducing Berserk CD is also nice, as now with each and every pull you have it ready.