Check the press-release in the announcement thread, which confirms 3-part harmonies and other details.
Most importantly though, you can find the HQ trailer here:
Plus photos and a downloadable trailer (for full-screen) here:
Seriously, this just blew me away. Without exaggeration, this is the single best trailer for a video game i've ever seen in my life.
Wow. The graphics, concept and gameplay all look amazing.