Sorry mate missed this.....I loved Rome Total War & I enjoyed the Civ games to an extent but putting a tank against a pike-man got a bit strange.Empire is really good but once you get the right formula you can just steamroll you way to a win if you know what I mean.
EU is a lot slower & the graphics are shit compared to Empire but the game play is a lot more involved. Getting your economy working would tax Gorden Brown OK bad example
If you like a slow game where you have to think out your strategy a good twenty years in advance then this game is the the dogs bollocks.
If when playing empire you were thinking were is the depth then try this I think it is about a £20 on steam but you can play the Europa Universalis III Complete Demo which will give you a good idea weather you would like it.