I felt very challenged by this campaign and the rest. The AI keeps coming after you with various groups of troops, and you can't leave your base open or they'll just wipe it out. You must use a variety of units and tactics, so that you are prepared for anything they throw at you, and they'll throw everything at you. Base defenses seem so formidable in this game, requiring air strikes or long-range artillery to remove before you go in with ground troops or you will face devastating losses.
With the story closed on this game, I'm very much looking forward to the expansion which drops next month. The additional campaigns and game modes promise to expand the game's life, for which I am very greatful!