A lucky member from GamerStyle.com has access to the Halo Wars demo earlier and posted up their impressions on the demo.
"The title screen had beautiful music that perfectly matched the halo style, depressing and a sign of remembrance to all that die in war. I quickly went to the basic tutorial which dealt with basic movement, construction and camera movement. The controls flowed easily and (I have to say) it was easier to control than most PC RTS games. Animations were awesome and unit voices were perfect and hilarious."