Well I just completed the Hill 318 missions. I have to say, I found the second really frustrating and spent too much time shouting at my monitor. While the first mission where I had to hold the hill used an RTS cliche, at least it was interesting and made sense.
The mission that followed, where I had to hold sectors of 318 to gain points just took me out of the game. Firstly it was extremely tough, but more importantly just seemed too gimmicky to be suitable for a single player campaign mission. It was the only mission I didn't like, though when I finally won, I was exhilarated.