One thing that is definitely remaining is the distinctive stances - fast, group and heavy. In The Witcher 2, they won't be as separate as before. CD Projekt are aiming to allow for players to mix them together to produce a better flow to the combat.
Potion creation will be made less fiddly this time - more a matter of just making sure you have the right ingredients without having to go through the whole meditation and bubbling cauldron thing. In fact, the whole issue of character inventory and progression has been addressed. While not a major issue last time, your inventory could get cluttered up easily, so there are moves afoot to make sure this doesn't happen so much.
We didn't get to play at E3 2010, but we did get a chance to see some of the game in action. Choice and consequence still factors into The Witcher 2's progression, as the choices you make in conversation affect how events play out further down the line. While in conversation you'll see the interface is much different, with a handful of short dialogue options appearing in the left middle of the screen as interactions play out. You're also given a limited amount of time to input each option, so you'll need to think fast as to how to approach each situation since the decisions can have far reaching effects.