Fighter jet have had HUDs for years and I've always been surprised that, at least to the best of my knowledge, this technology has never before found its was into automobiles.
In terms of safety, I think this technology should be just as, if not more safe, than using the more traditional dials found on automobiles. Traditional dials require you to move your eyes from the road down to the dashboard. Using a HUD you don't have to move your eyes off the road; you look through the semi-opaque display to see the road.
Nothing says "this exciting new feature is ready to help you conquer
the road" quite like a subtle gradient from light grey to dark grey- good work GM
It's not as thrilling as a alert flashing in red when an incoming heat seeking missile is locked onto your location but it's a start at making the driving experience a bit more exciting.
You can view more information on the GM website here.