So I got the chance to actually play it, and it's pretty much what I expected.
You feel constantly hamstrung by the stupid loadout system. It's frustrating having an enemy get away with single-digit health when normally you'd just switch to MG/LG and finish them off. Melee attacks are probably the worst thing to be added to this game so far, and the stupid execution animation is terrible and totally ruins any sense of momentum in the game.
The double-jump feels a bit awkward although with some tweaking to the movement mechanics I feel could be salvageable. I dislike the edge grab/climbing because of how much it kills your momentum, but I appreciate there's a bunch of stuff in the map design that wouldn't really be possible without it.
I agree with people saying the revenant should be a separate game mode. I didn't really enjoy warpath and it just felt kind of tacked-on. Oh, the gauss rifle is a pretty cheesy "welfare points" addition too.
Things I did like: the maps seem pretty good (multiple route to various areas of interest and little hidden bits here and there), quad + shotgun is as satisfying as ever, damage number overlay is useful feedback.
I won't be buying it because with their currently released DLC plans, online will be dead by the first pack release (if not earlier).
Having been so negative, I have actually had fun with it (I played 4 hours straight just now) - I just don't think it will have any lasting appeal to the mainstream, and I don't think it has enough depth for a more dedicated fanbase to keep it alive. Who knows, if people start hosting tournaments and stuff and it begins to gain traction I will gladly eat my words.