I finished the Starcraft Terran campaign over the weekend and got halfway through the Zerg campaign. The Terran music is really stuck in my head. It's actually good, even with it's late 80's cheesy synth horn stabs, and staccato riffs.
I am definitely liking SC a lot more than WC. Though Starcraft has no difficulty setting, it does have saves/reloads and, most importantly, a speed setting so I can manage large battles a lot easier. But Sammy is right, the pathfinding really sucks. Units wander off into unexplored territory and get hammered - I chastise my computer. Not pretty.
In general though, it's been fun and addictive. One major gripe is that some of the later missions seem impossible to win the first time, without prior knowledge of the map and enemy attack patterns/scripts.
So far, I like playing the Terrans more than the Zerg. Maybe I haven't mastered them yet, but Zerg invasion forces are very hard to manage compared to Terrans. Unit management in RTS's has always been a bit of clusterfuck that really annoys me…