You control small "squads" of 4-6 units, which gain experience, level and upgrade (a squire for instance becomes either a knight or an inquisitor, different strengths), magic is used outside of battle. There are four sides, the Empire (humans), the Mountain Clans, the Legions of the Damned, and the Undead. The art is beautiful even today if you ask me.
I actually preferred Disciples 2 over Heroes of Might and Magic 3
Which is why I am so nervous/anxious to see what happens with the franchise. Note to self, go see how Disciples III is shaping up.