Be advised, if you've already seen the hour-long gameplay demonstrations, this demo is hardly worth your time.
One, honestly kinda annoying, tutorial mission, and a choice of two different others after that.
Plus, you get to meet some of the home-base people who talk to you a bit.
The missions are easy, I will assume that it's locked to Easy or Normal difficulty.
If you have no idea how the game plays, then by all means, try it out.
But otherwise, it's mostly just a waste of time.
Demo wasn't worth the 40 minutes of download time though. Much too short, with zero new information to people who have kept an eye on the game over the last month or two.
Disclaimer: Yes, I already preordered it, and I fully expect to love the actual game.