I spent a lot of hours playing this during my childhood. Actually it was my first game ever I bought for my own money. Every campaign is unique and strongly differentiated by its level of difficulty. The actual gameplay feels very good and you have to actually think during the play on the map. Sometimes it is essential to know how to move with your army. Battles can be very massive and extremely fun. Only downside is that when your hero falls the game ends immediately (no chance to revive him etc). This is actually pretty logical -> but given the possible size of armies and following chaos on the map you will found out that it is very difficult to manage your hero and army separately. Some of the missions are extremely hard to finish. But the rewarding feeling after their completion is awesome :D. The game uses concept of heroes which are unique and have different abilities. Their usage is essential in the battle -> but also their death is fatal and it means end of the game for you. You have to think not only about their movement and health but about the actual timing of their special abilities and use them properly. There is also a quite good encyclopedia within the game. You can read some background information about characters, units and fractions. I would say this is the forgotten gem of the past. It is worth every penny for sure.
