Just looked at some of IGNs game play videos... game looks dope... check out the one called "Huge Gameplay Demo HD"
New units, + TONS of units on screen at once.... and my favorite improvement that I saw... you can select more then 12 units at once(in the video's case, they had 20 units selected, plus im sure u can select more)
http://media.pc.ign.com/media/850/850126/vids_1.html