I haven't played it yet but if you are thinking about getting it this is the week. Steam is having their holiday sale right now. It's currently only 16% off but it was already one of the daily deals during this sale at 40% off. If you wait until the encore day sales start on January 1st it is highly likely that it will be 40% off again.
If it doesn't drop back to that same price on the encore day for whatever reason it will still be available at 16% off until 1:00pm on January 2nd. Pretty much everything goes back to it's best price point on the last day of the sale though.
From what I have heard, there isn't enough to do in the game yet. I have heard people say that it's going to need a few Civ V style expansions before it feels like a full game. I'll probably wait until one or two of those come out and gets bundled with the base game before I pick it up.