Disregarding Verb's esteemed post, I've played Civ 4, Rev, and a little of 5. 5 being the best one.
If you like the idea of a strategy board game then go ahead. It's also a pretty cool way to learn some history (encyclopedia on it, wonders description, etc). If you get it, be prepared to actually take the time to learn how to play, and invest many hours into a single playthrough. The games can take quite a bit.
I personally think the series is great. You can always try the demo they have available too, which I'd honestly recommend. If you like it, than get it. $12.50 is a steal for that game.