Hills, trees and contours are essential to your plans. Getting the right terrain for your army composition is essential. Units all have strengths and weaknesses and with the huge armies and varieties of troops no battle result is predetermined.
Morale, and having fresh reserves if used in a timely manner are often the difference between being routed or victorious. All the clans have specialties and samurai armies must just be about the most colourful of any period in history. And since its feudal it leads itself to a campaign type game.
The maps are great and the intrigue of having a dozens of clans all of which interact and have their own agenda can be quite stressful. Throw in the characters and all the technology upgrades and the complexity becomes fascinating. There are also mods you can purchase for a small price that allow you to pick any clan in game to give endless variety.
Add in naval battles.
And the detail of Ashigaru and Samurai armour and the game stands out as a good recreation of any wargaming battlefield you could set up. If you are a gamer and are interested in the period you can't go far wrong with Zvezda's 1/72 range of figures