I love this soundtrack, every track is great. There are three different tracks for every one of the different playable races, and they all bring their own unique mood and sound.

The Zerg ones are my favorite, followed by Terran and Protoss last.

The Terran soundtrack comes closest to conventional songs, with steady drumbeats and keyboard and electric guitar melodies. The Protoss soundtrack has a ethereal quality, lots of drawn-out strings and synths. A bit moody and dark as well. The Zerg soundtrack has a nice mix of electronic instruments, percussion and fluctuates between long, atmospheric bits to active, lively parts.

As a long-time StarCraft 2 e-tournament watcher I'm a bigger fan of StarCraft 2, but the OST for part one is the best.