I will quantify my reply with i only was any good at Warcraft when it was an Rts. I always stunk at most other ones. I liked Starcraft because i had friends who would have fun with it and take it easy on me so i could experience the game, before they destroyed me. Campaign always held my interest until about half or three quarters of the way through then it got too tough for my brain to keep things straight.
I got SC2 for Xmas and i think i played about 6 of the single player campaigns, more or less, then i just lost all interest in it.
Not sure why, maybe because i just cant seem to get good at RTS games overall, but the story just didnt interest me as much as the Warcraft games or even the original SC.