I've been a huge fan of Sid Meier's Civilization series for a long time. My younger brother and I used to play CivNet, often both of us sitting in front of the screen discussing whether it would be better to research The Wheel or Bronze Working first (I still think that chariots are better), or deciding if we should build a new city by the river or near that mountain for mining. But Civ has come a long way since then.
The graphics are prettier, most definitely, but there's been quite a few changes in the series over time. They've added religion, better diplomacy, more wonders (of the world), and more. It seems that Civ5 however, is making the biggest change of all. Hexagons.
For years the Civ series has been played on a world map made exclusively of squares. Squares allowed for 8 directions of movement (4 cardinal directions, 4 diagonal), but now there are only 6. This allows for a more natural (and really beautiful from the screen-shots) looking map, but some people are complaining that it limits movement. I agree, partially. I think that from a world exploring standpoint, this will be a bit of a limitation, but for a unit combat point of view, this should allow for a better battle. No more can an enemy unit escape your wrath (and there's lots of it, especially after the Aztec's nuke my capitol) as easily as before. And since another big change is one unit per hex (thereby negating the old "stack tons of units into one unbeatable square" strategy), it should allow for both flanking and surrounding tactics. This I like.
One thing I should also mention about combat, is that now each unit has hit-points. Previously, units in combat would measure it's strength vs the others weakness, and whoever was higher won. The other unit was simply destroyed. Now each unit can survive an attack if their hit-points aren't wiped out. For example. I have 2 swordsman, you have 1 tank (I know, it gets like that sometimes. It's part of the fun). My swordsman each do 2 damage to you, totaling 4. But the tank has 7 hit-points. You've got 3 left, and can run away, or heal, or whatever. (Disclaimer: These numbers are made up for examples sake. I don't know what the stats will be).
The other thing I'll mention is that the hardware requirements for running Civ5 are pretty beastly. You'll need a fairly current computer to run it.
* Processor: Dual Core CPU
* Memory: 2GB RAM
* Video: 256 MB ATI HD2600 XT or better, 256 MB nVidia 7900 GS or better, or Core i3 or better integrated graphics
* Processor: 1.8 GHz Quad Core CPU
* Memory: 4 GB RAM
* Video: 512 MB ATI 4800 series or better, 512 MB nVidia 9800 series or better
If you've got a computer built in the last couple years, it shouldn't be too big of an issue. You might not be able to turn on all of the eye-candy, but the game should still run, and you'll have a good time. Turn on all the eye-candy, and you'd better have a pretty new computer, or it'll run so slowly you'd be better off watching grass grow. Myself, I'm not made of money, but I DO have a fairly new computer I built on-the-cheap with parts i bought individually (thank you NewEgg.com and eBay), so I'm good.
Civ5 is a turn based game, which may be a bit of a turn off for those people that play games like Age of Empires and StarCraft2. I assure you, civ is one of the most addictive games of all time. There are stories of people losing entire nights sleep to get in "just one more turn". I've even heard stories of people in relationships having fights over who gets to use the PC, they both want to play Civ. I've never heard of a Civ related divorce, but some people are crazy, it's probably happened.
Civilization 5 is due out September 21st. So either check out your local retailer, as many have pre-order options, or your favorite game service such as Steam and pick up a copy. It's a measly $50 for the newest installment of one of the greatest game series of all time.
More info at http://www.civilization5.com/