I've only played two full games at this point both on the Noble difficulty. The first I won by Space Ship and the second I won by Diplomatic means. I have noticed a few things about the game though that I'm not sure wether or not I like yet.
Firstly, early wars seem to be almost impossible. Even if you wait until you get Swordsmen it is still very difficult to do because of the tech pace. The units become obsolete very soon it seems to me. I haven't been able to conquer my own continent yet, which I did regularly by the time I had Knights in CivIII.
Secondly, religion makes diplomacy very easy in this game I find. Found a religion early, and spread it throughout the continent. That's basically how I won my second game diplomatically. Not to mention the extra cash you get if you build a shrine and the spy potential of having all your enemies cities under your religion.
Thirdly, the interface seems unfinished to me. I know it is supposed to be easy to navigate and user friendly to the newer people to civ, but I have had a hard time with it and still am. I just get the feeling that it was unfinished. I prefer the old CivIII interface much more, but that will probably change as I play more CivIV
Don't get me wrong I love playing so far, but I don't know. The game seems to just move way to fast for me. I guess I'll try ramping up the difficulty and playing a Large instead of Standard map. Maybe that will help with the tech pacing.