Sorry, can't remember which vid, but it mentioned sliding and knocking people down as overpowered atleast.
Here is what Richard Ham said on sliding:
"Slide is basically hitting the crouch button while sprinting. You can spam them like crazy, but on the whole, you'll end up being a little slower that just sprinting normally. It's really there as a defensive maneuver (smaller low target), to get under low things, and as a melee attack...don't worry. it does no damage at all, and i don't think anyone would complain of it being overpowered. it's part of the broader melee package that's i'm not supposed to talk about but which has a very different approach than the standard shooter fare. I imagine there'll be stuff revealed about it in the new year. "
The only thing that they considered overpowered, were sliding finishing moves, as explained by Neil Alphonso:
"We experimented with slide fatalities (we never called them that, I'm just saying it now because it sounds cool), but it made it too easy to finish somebody off, while making yourself a low profile target at the same time."
Also, as far as I know, slide tackles are still in.