I've played through mounds and mounds of crap games and its been years since I played a good one... till now.
This is so much a better single player game than the first Starcraft, mostly in the fact every single mission is unique in some way, and doesn't bore you down with too much repetitive back and forth unit killing to win. There isn't anything revolutionary about the gameplay... but its about as refined and polished oldschool rts controls can get and are almost identical to the first SC, but work even better now.
Blizzard did a really great job telling almost every part of the story from the first Starcraft to help understand things which is great. The level of professional quality of the cutscenes is something you rarely see in any game, and completely draws you into the games characters and instantly creates a believable world.
I don't play RTS games online so I really liked playing one with this level of care put into the single player part of the game. Only thing I can complain about is the game is too short. The first Starcraft is a bit longer, and the expansion is probably twice as long as this game...
That being said, quality before quantity... and Starcraft 2 is so much better in every way...