Ehh... count me among those who didn't find it much fun.
It was an interesting exercise, but the SIMULATION guy preaching at you started to wear on me after a while. It's like he's trying to discourage you from working for the GTVA (if in fact that's who's providing the simulation). And I'm not particularly a fan of RTS games.
The switch from "simulation" to "real life" in mission 2 was interesting, and unexpected, but it didn't grab me emotionally like it did for some other people in this thread. Maybe it's because I didn't feel immersed in the simulation.
The last mission was rather frustrating. Considering how badly I did at the first three missions, I was very pleased to actually be in a winning position after several rounds, with the enemy installation down to 50% and my own somewhere around 80 or 90. And then all the IFFs changed over, and I had absolutely no chance to recover, and ended up losing.
There were also some bugs in the last mission; by the end of the game there were three enemy and one friendly wings that were just sitting there, refusing to attack anything. None of the orders I gave the friendly wing worked. Also, according to the mission file, it looks like there were supposed to be a lot of messages that triggered after the escaping transport appeared, but none of them showed up. I was just dumped out of the mission with no debriefing.
I wanted to go back and play the last mission a second time, to see if I could do any better (keeping in mind the IFF change), but Ransom forgot to add the Tech Room to his custom main hall, and I didn't feel like playing through the entire campaign again.
So, for me, the fun factor was only maybe 2 stars out of 5. The technical achievement factor, however, was an easy 5 out of 5 -- I was very impressed with the idea, the fact that Ransom was able to kludge an RTS interface out of an FPS interface, and the sheer amount of stuff that he attempted in the campaign. And based on the number of questions he asked me over IM, I'm surprised there weren't more bugs than there were.
As a FREDder myself, I think that this a pretty amazing achievement.
As a proof of concept, it's very thought provoking, and definitely pushes the limits of what you can do in a campaign.