A quality, standard-setting RTS that, in my opinion, ranks as one of the best games ever.
Although criticised by many as being simple and actually a little behind some of the RTSs of its time (Total Annihilation), i think that it still stands as a great game. The races are balanced, all with their own strengths and weaknesses. You don't feel that anyside really has the upper hand from the start.
I really enjoyed playing through the story-mode. Besides having a good storyline, the missions themselves were varied. I especially enjoyed one of the earlier missions, i can't remember the name of it, but it involved defending your base for 30 mins, culminamting in a HUGE attack from the Zerg swarm.
The map editor was one of the most advanced of its time, featuring varied toolsets, doodads and triggers which could be used to create very professional maps. Not that i have the patience or skill to do such things, but the tools were certainly there.
However, Starcraft does feature some negative things. First of all, the queue and selection system is primitive to say the least, and the graphics aren't top-notch either, even for that time. And contrary to what i said above, the multiplayer is slightly imbalanced, with Prottoss rush tactics using Zealots usually gets an easy early win.
Besides these problems, Starcraft is a great game which i would recommend to anyone.