Fantastic pack for $20. I love the Commander's Challenge. The campaign is ok, not great, but... $20.
I've wasted weeks on this game (enjoying every minute)... is it worth two movie tickets? Uh, YEAH!
The only change I'd make would be to allow saves in the Commander's challenge. Its a bit of a pain to start every one from the top each time. Or, if you are trying to keep it fair (so you can't cherry pick only your best performances), at least an autosave every 2 or 3 minutes so you don't have to keep repeating your opening moves trying to beat the par time.
In summary, this is a fine game and GameSpot has really missed the boat on their review of this one. I, for one, did not miss multiplayer at all... I still have Red Alert if I want it.