For example, with one of my current heroes, I have 3 slots on my front line, but I can only have 4 soldiers total. If I put my two knights right next to each other, the one with the middle slot will be attackable by all three of the enemy's front line troops. If I spread them, however, my soldiers will last a lot longer. Also, each troop has an initiative rating, which determines the order of attack. If I get the first attack with my ranger, I click on the enemy portrait and watch my eagle fly across the map and take a chunk out of that enemy archer.
Battles are quick and tense, and quite interesting.
If you want a really good feel for the battles, check out the demo and screen shots from their web site. Gameplay, like any other turn-based fantasy game allows you to move each hero a certain distance each day. This allows for some interesting strategy. For example, I had a city about to come under attack and all my heroes were far away. I only had enough gold for one hero and two swordsmen, so I hired them, cast two good chain lightning spells on the approaching party and watched them turn tail their next turn.