Total War Vs Civilizations

My friend got me into Civilizations which I love, although I have not played in a while because my games I currently am in are deadlocked or stalemates, and I wanted to try Rome Total war because there's online play and we could play together.

The real discussion here is
-What is the downside to the total war series?[/list]
-Is the replay value the same as Civilizations?[/list]
-Main differences for those who have played both and or one[/list]