Empire Earth does not bring anything particularly new to the table in the real time strategy genre. Even at its release the graphics were nothing special and it plays very much like the classic and groundbreaking Age of Empires II.
That said, the concept is very groundbreaking. Empire Earth is probably the only game that allows you to play through so many periods of human existence. You may play through 14 epochs (like the "ages" in Age of Empires) and start with humble cavemen and eventually work your way to powerful mechs. Additionally, as you play through the single player campaigns (there are four plus a tutorial) you will play through actual historical events.
Though hardcore real time strategy fans may be looking for something more, Empire Earth offers excellent single player campaigns and a classical real time strategy experience. Fans of Age of Empires will hit the ground running with Empire Earth. Getting this game and its expansion for $5.99 is a bargain strategy games should not miss!