I am a big fan of the AOE series, and history. This game is brilliant, although the AI may be silly at times *cough, Napolean* it still has unique gameplay and good graphics, as well a Pretty decent uprgade system. I loved the fact that different units would take up a certain amount of population, e.g. A dragoon would take up 2 population where as the a musketeer would take up 1. There is a huge variety of map choices and with the Asian dynasties pack and The war cheifs DLC, the selection choices are endless, they vary from the Amazon River, The Andes, Anywhere in the US and even the Great silk road in Asia.
Best feature for me? The Expansion Packs were actually expansions that changed the game in multiple ways and added on to the complete/full base form of the game. normally DLC nowadays is required to get the full package of what the final product should've been. AoE3's Expansion Packs ARE NOT DLC. The Expansion Packs in AoE3 add on to the game content enough to make it feel like a different game within a game. The Expansion Packs aren't neccessary to fully enjoy Age of Empires III; however, having them improves upon the player experience greater.
If you enjoy real time strategy games, enjoy managing an economy, epic large battles, and don't like excessive micromanaging then this is the game for you. It offers brilliant combat with amazing scenery. The unit mapping is rather brilliant and the variety of maps keeps you constantly wanting to play more.