I've been playing Civ 5 for a few days and it is really great. The reviews were right. It is worth the money.
You have the love the new hexagon grid! Much smarter than the squares/blocks. When your culture expands it only expands to ONE grid. However you can BUY new grid spaces if your culture hasn't expended to a grid that you want. You can also expand three grid spaces away from your cities.
Also you don't automatically create your capital when you create your first town. You have to build the palace in the town that you want to be your capitol.
My favorite change is no more stacks of doom. YAY!! You can only have 1 land combat and 1 non combat unit in one grid. So those stacks of 40 units coming from the enemy are no more.
You can only fortify one unit in the town. However the town can develop its own defensive abilities. Even ranged attacks. So it’s pretty cool.
They did a lot more work on the AI as well.
For example: I built a town about 3 grid spaces away from another civ and he contacted me and said: "Don’t you think that you've built your town a little too close?" You then have the option to say "I can build my town any place that I choose" or "I won’t build any closer". Your answers change your relationship with that civ.
City States also give you tasks that can change your relationship with them. For instance they may ask you to destroy a barbarian encampment that is near them. If you do defeat the encampment your relationship with that City state increases and they give you money, etc.
You can do other things to increase your relationship with them like give them food or resources. It came in handy because I had a civ declare war on me. The two City States that I was "friends/allies" with also jumped into the battle and the Civ contacted me and he gave me two of his cities and all of his gold and begged for mercy. It was pretty cool.
I did notice a few downsides..
1. A Civ contacted me and asked me to sign a secrecy pact with him. (at the bottom of this prompt it said "This action will not start a war") But nowhere in the game does it explain what a secrecy pact is! Not even in the civilopedia. So if anyone knows what this is.. Please tell me!
2. The civilopedia crashes my game to the desktop. It happened often enough to be annoying.
3. You HAVE to connect to STEAM in order to play any multiplayer games. Even LAN games. You also have to connect to STEAM at least once to activate the game to be able to play it even in single player mode.
That about it for now. It is worth it so if you are a Civ junkie and are holding out go and grab a copy.