You play Darth Vader's apprentice after Ep III, and spend your time rounding up the remaining Jedi. (I honestly don't know how difficult this could be, since DV and the Emperor managed to take out the two toughest Jedi, and the remaining ones are so weak they couldn't see a little thing like, say, the Clone Wars, or even the Emperor being a dick). There are two main things I've been looking forward to in this game:
1) Playing as a Sith apprentice
2) Objects breaking in realistic ways.
So I saw last night that the demo was out for the XBox, and I gave it a try. In reverse order:
2) The physics is basically used for doors and windows. This is actually about what I expected, though less than I hoped for. It's nice, but not nearly the gaming nirvana that the hype makes it out to be.
1) The action is actually more fun than I expected. Tossing troops around, jumping in air (though I haven't heard a justification for the double jump, other than "it kicks ass"), throwing your lightsaber, crushing enemies... it's all quite fun

My only real complaint is that the lightsaber doesn't slice enemies the way it did in Jedi Outcast or Jedi Academy. Instead, the violence resembles the films more, where enemies just fall down.