Whoa.... I have played it all night and I don't totally love it nor am I totally hooked
Like:
I do like the tactical combat and the fact that civilization advantages are linked to Culture. I always thought the abstract notion of unit stacks was a little inane. Combat was never compelling and at most a necessary chore. Now it is fun. Culture accumulates like in Civ IV but instead of only expanding your territory it now unlocks societal enhancements. I will definitely have to take more time in planning those in future games.
Unsure:
There are a number of changes that I am unsure about. Firstly, the shift from each city having its own happiness to a societal value changes the dynamics a lot. Now the consequences of unhappiness impact every aspect of your society. On the flip side building a coliseum in one city has an impact on all of them. The biggest thing you will notice about this is that trying to take over other civilizations cities quickly ramps up discontent. That makes it an hard to try and take over a lot of enemy cities in a short period. Next up, roads/rail now have a cost to maintain them so your workers are not out there building roads incessantly. You still want to connect your cities to create trade routes but there is a cost benefit to building roads elsewhere. Finally, neutral cities don't seem to be doing much of anything and seem to be a distraction for most of the game.
Dislike:
My biggest dislike is that the game now seems to take ages to do a turn. I am running on an I7 chip with a 60 GB SSD. Nothing should take long and yet there is a long lag between turns and I don't know why. Not far behind that is that fact that building a wonder has become a big meh… you don't feel anything about building one. In this sense I feel that the game has gone too far towards the abstract feel of Alpha Centauri. Next is the lack of a hurry production for anything especially for courthouses. Courthouses are the only way to make captured cities really one of your own. They take a long time to build an all the while your society is being dragged down by negative happiness of the new acquisition. There isn't a hurry production option now all you can do is buy some buildings outright if you have the gold. Lastly, I am not a fan of the new interface. It seems to be focused too much on the pretty terrain and doesn't show enough of the map or city information when you are in a city.
My Advice:
I went out and bought this the first day based upon the glowing Gamespot review. Definitely try the demo and if you like the changes they have made go out and buy it. If you don't like the changes stick to Civ IV.