I wasn't able to get a beta code so my opinion is kind of useless. But from a spectators perspective, the game seems a bit slow. The animations are more fluid than Injustice 1, but since NRS slowed everything down characters movements are still noticeably stiff. I think if they sped them up a little, the rigidness would be less obvious and the game play would be a bit more exciting.
There's no reason the clock should be so small, especially with how frequent timeouts occur. Make it bigger.
A little disappointed on how much NRS copied and pasted UI elements from MKX. They say they want MKX and IJ2 to look and feel like completely different games, but that's not helping that aspiration.
I have mixed emotions about some of the stages darkness. But players haven't complained so I guess it's not a big deal and adds to the cinematic appeal.
Outside of those things, everything looks great. Can't wait to play Swamp Thing.