hm, you know what? After playing it a little longer I've come to the following conclusion:
the graphics are great but the actual gameplay doesn't really differ a lot from any other RTS-Game I've played so far. I don't think I'm gonna buy it, instead I'll save my money for TES: Oblivion and get some nifty new CPU and graphic card. well, I'm off to play Earth2160 now again *kicks the AoE3-Demo into the trash bin*...

"One day before Oblivion is released, you'd better buy the best hardware components available for money..." - Todd Howard