Was umming and Ah-ing about whether to get this, then I saw the magic words "Steam Cloud" on the store page. For me that's fantastic as I flit between my laptop at my girlfriend's house and my PC at home.
Played it for a couple of hours last night, and was pleased to see that to all intents and purposes you can just jump in if you've played Civ before. It looks nice and sounds good, I guess all the new features will wrangle their way in as I play!
Unfortunately I didn't click the "Steam Cloud" box when I saved last night, so I'll just have to do it all over again (shame, eh?)