I think I'll put on a point that I kinda think about when people say about the kid dying scene being forced.
What Bioware I believe was going with was generally the idea, "You can't put a face on a million people."
Now, how well they did it in the demo I wasn't too OMG about, but the idea to me was, them saying a million people died due to the reapers landing is somewhat of a player punch, but it hits a lot harder when you know people who died.
Good examples would be in the other Mass Effect games, *SPOILERS AHOY*
A companion of yours dies, somebody you may have grown to see, maybe even really liked, then they die. It's a lot sadder than hearing "Oh, a planet was blown up."
Now, the scene I felt was sad, it's not a faceless soldier who died, it was somebody you met, and actually spoke with, it wasn't a -very- sad scene, but it did have an emotional note.
In general though, I thought the demo was decent, I am sad they took out some of the choices for the demo, but it wasn't too bad, really the spacebar doing everything was what bugged me more than anything else.