I must admit, I am a little disappiointed. Some thoughts below:
*I was expecting a cool cut scene when I was going for the Scientific Victory. You only get a stock 'photo' and a bit of an explanation.
*The AI isnt very bright. It seems to have no grasp at all of how to wage battle (not that Im much better).
*City states get very agressive and cocky once you get allies with one and ply them with advanced units (I gave Stockholm a Infantryman and he went bananas attacking the Aztecs)
*I kept getting messages from Ghandi and others 'threatening' me. It didnt seem much like a threat, but It also was not a friendly chat. They were annoyed with my warlike ways.
* While I do like the policy bonus features, I do miss Religon. There is no option for a Crusade! now
*I still think Flying units are just too difficult to make work properly. By the time I have them I still fight my landwars with tanks, infantry and later the Giant Metal Robot

. Ive NEVER built a Carrier in any game of CIV I have played.
* I wish there was an option to make units auto attack bandits if they find them while exploring. I lose workers when they set sail to parts of my lands that need attention. The unit destroyed only tells you a unit has been destroyed, it does not tell you WHAT unit was. My Frigate and later destroyers would really benefit from that.
* I was hoping that you would be able to do something with Mountains esp in the later ages. Deep mining? I assumed some future tech might help. On some maps Ive restarted if there are too many mountains.
* Does future tech do anything but boost your final score? If not, this seems a bit wasteful.
Final: I am still finding Civ 4 .. better. I dont know why, that game had some faults also. Civ 5 just seems to lack in certain key areas. Although to be bluntly honest, I realy wanted an Alpha Centauri 2 over a Civ 5.