I am a fairly big fan of civ / empire building games in general. I played CoC for the first time last wednesday at a friends place and proceeded to buy my own copy yesterday. The first game was just a learning game as we started at around 9:30 and only had an hour (definately not enough time for a four player game). We got through the first two rounds and got a feel for how the game progresses.
In my opinion this is just an expansion away from adding additional units / advanced ages/technologies. Which will be fun to see. I really hope there is or will be an expansion in the works. Imagine, if you will, a tech advance that allows you to place an "age" over-lay on your tech tree. With the way cubes go into slots it would be easy to add advanced ages with modified technologies that just fits over top of your current board.
Great game so far, look forward to playing a full four player game sometime soon. This will fit well between game of thrones and twilight imperium 3 in my opinion