Excellent review! Everything you said hit the nail on the head. For me, the game was undermined by the campaign and redeemed in multiplayer. During the single-player campaign, the AI is often unreactive, letting itself be whittled away by superior forces. At the same time, the campaign contains scripted events that add AI forces to the map... occasionally in the same real estate that the player's units are currently operating.
As you point out, there are no useless units in this game. Multiplayer is consequentially very entertaining, with players coming up with contingency plan after contingency plan, racing to conquer the map or liberate artifacts from the center of the map.
I own a copy of this game, and would buy it again if I lost my copy.