Sub Zero is still a fun character to play, and he has some good combos. Here's my impression on him so far from both the demo and the PAX build.
He is easy to pick up if you are a casual player and only do specials and short combos.
He is hard to master if you like long chain combos. He has no good pop ups, so in a tag match, his partner makes a huge difference in his combo abilities.
His slide move has been gimped because now you can't use it while the opponent is on the ground. It goes right through. So you have to time your combos so you're ending it with the slide before they hit the ground.
His ground freeze is, as we said, practically worthless.
His X-Ray goes right through you if you're too close when you use it. Unless it's working as a counter of course. I like the fact that you have the option to use it either way.
My advice if you want to do some bigger combos is this.... Combo INTO the freeze. Don't start with it. And don't use 2, 1, 2 then freeze. That does work, but the position and distance the opponent ends up in makes it hard to follow with anything other than one or two hits.
I like using f+4, then freeze, then your longer chain comob. Or b+1, 2, freeze... etc.
He's a good character, just not easy to master and some of his moves aren't very effective.