I’ve played every Civilization game since the first one came out in the early 90′s. When you play a game a lot it starts to shape you. You internalize the game model, and start applying it to other things as well. I think the Civ games shaped how I think about long-term projects, about how to manage resources to reach long-term goals. Ideas like that can be powerful when they’re introduced stealthily by way of having fun.
What’s new in Civilization V is that it feels more focused, more like a board game. This is a good thing, because board game makers are good at stripping away unnecessary complexity. Civ V is still an order of magnitude more complex than similar board games, but it feels more focused than Civ IV. (But do remember to turn on the hex grid and the resource markers, or everything may as well run on magic.)
The largest problem with the Civ games have always been their addictiveness. Looking up to find that it has suddenly become morning is not unheard of. But this isn’t dangerous if you’re prepared for it. I play only in one hour batches. After that it stops being fun, and starts being compulsive. A Civ game should be a garden you to tend to over a long period of time. And then you go do something else inbetween.
Or, in Civ terms: If you dedicate all your citizens to working the Civ resource (0 food, 0 production, 0 gold, 0 science, 0 culture), your empire will decline and fall.