What I liked:
-presentation
-most of the simplifiying in the name of scaling down game (religion, worker units, tech tree)
-exploration/espionage system
What seemed unbalanced:
-I find Angkor Wat -> Builds me pyramids -> Communism + Iron Working three techs in the game! Crank Legions and conquer.
-The road system seems exploitable to me. I mean, the easiest way to move troops at an enemy is to send a settler first, make a city right next to enemy border, connect road, then send hoardes up that road.
What I didn't like:
-The return to x/x units! Civ IV did many things right, but imho, the switch to a single value rock/paper/scissors mechanic was the main innovation. Very sad to see it go.
When they had the podcasts Q/A about this game half a year ago, I asked about improving the tactics of the combat system, and they replied with something along the lines of "this isn't a tactics game, it's gotta be simple enough on several aspects to function without one aspect upending the other." Well, fair enough I suppose, but speaking for myself, that's not what I wanted to hear. The strength in having a deep tactical system is that there was the possibility that even when stuck with a starting locational, overall size or empire management disadvantage, there was hope in "smarting your way past it" by simply fighting smarter.
-It seemed to me that a 11 to 10 attack has a 10% chance of winning. Correct me if I'm wrong. But I liked in civ IV that there was a bonus for "being right", a reward for smart tactics.
Oh well, that's just my initial impressions. Overall I will buy it and play it, but probably won't get as obsessed with it that I did with Civ IV. Oh well.