Just my opinion after playing civ for 19 years and civ V for a few days:
The great change is from SoD to 1UpT. I believe both options are good. But this change alone makes a new game.
This means a new balance should have found. Was it? I'm far from sure.
A new factor, and big one, enters the equation: the number of "convenient" tiles.
And the fact that tiles were changed from 8 sides to just 6, enhances this.
So, less miltary units are needed, both for offense or defense. The consequences are
not just for the "warmonger" part of the game, but for all. Do the differences on the
"builder" part balance it or not? Not sure, yet.
Happiness that is supposed to be an essential balance, seems can be ignored after the
initial part of the game (I have to check it again).
Then, there is what I call the interface things:
The manual is poor and even wrong sometimes.
The AI is very weak. (For instance a melée AI kept itself a 2 tiles distance from a
ranged; and no, it was not at settler level).
The game is to be activated from an internet plataform. Nevertheless, no PBEM, no
sequential turns and no good central,unique staging room for the "true" simultaneous,i.e. the ladder style.
If this game was something 1 would be very good; but it is CIV V.
I do hope they who concern do now and in near future what they should before sell.
I am still a Civ customer and want to remain so.