Some interesting tidbits about the singleplayer:
There is a train level, in which wind actually slows your movement because it's going so fast, and there's a whole bunch of stuff flying around while it's going on.
You actually get to use the mech from the trailer.
Leaked on NeoGAF, and confirmed when Tempy, a GG dev and NeoGAF frequenter, tried to fine out who the guy was so he could get him in trouble for breaking the NDA, lol.
http://www.neogaf.com/forum/showpost.php?p=13396731&postcount=495