2. Wait a minute, Earth is getting smashed by the Reapers and you're off helping Wrex get laid? (and how does that work if you let Wrex get killed back in part 1?)
Didn't they replace Wrex with some other guy in 2 if you got him killed? Presumably his role in his mission is either filled by that other guy, or Grunt, if he's alive. Likewise you could have gotten Mordin killed in 2, so presumably he would be replaced as well. If you notice the loading screen between the first two bits, the second section takes place a good bit into the game from the beginning, to give you an idea of what a leveled character with a developed squad can do. From what they say, it would seem that what you're doing is securing the support of the Krogans in the war. The plot in this one seems a bit like Dragon Age's, in that you'll probably be going from place to place trying to convince everyone else to help you fight. Really, if I have any issues with the plot at the moment, it's that the Reapers seem terribly inefficient at their job, since wiping out all life on Earth should be the work of minutes when you have the capability to send half the asteroid belt crashing into the Earth.
Anyways, I liked the demo, I like the new moves and the branching leveling trees. I went soldier in the demo while my Shepard is an Infiltrator, just to try it out. Not too bad, but I had a hard time of a few of the fights. The combat is very chaotic with enemies flanking all over the place. I liked the Kinect support, you can really do anything via voice, although I'm likely to use it more often to change weapons, ammo, and activate modes rather than to direct attacks or in dialogs. I need to get used to the controls, I kept hitting "B" to dodge or take cover, when the actual command in this game is "A", so I just kept taking swings at the air.