About immersion, the more I think about it, the more I believe I'll be more immersed with VI graphics, because they are consistent in their abstraction. I can see the map as... well, as a map. I see a forest as a representation on a map of the forest in that area etc etc.
In V there is this inconsistency. You get this awesome realistic looking map, and then you plop ugly cities on it, you cover the land with improvements and it's awful to look at, you build roads and... I won't even go there. That realistic looking terrain and then there's civ scale of everything, continents, distances etc. etc. The more I look at side by side comparisons the more inconsistent and weird V style looks.
That, plus a lot better gameplay than V (and it really cannot be otherwise this time, as this is not a "IV > V" full on revolution, but rather "add and improve") will definitely immerse me more. Good example with graphics for myself is the fact that despite me never going back to IV after V, I was never as immersed in V as in IV.