The windward side is packed smooth and hard. This effects unit movement depending on which slope you are traversing. If a prerequisite building is destroyed, you lose access to the Unit. Here is the latest update from Stuart and his Melange article. The entire thing can be found here and as always sign the petition on the messageboard .
Higher ground provides bonuses to attacking damage, and firing and sight range.
You can also use the terrain as cover. Tidal Dust Basins now vary in fineness. Some are only a danger to heavy Vehicles. The more volatile Dust Chasms are a danger to any unwary Unit. It will be tremendously difficult to target Units inside the storm.