With so many changes, tweaks, cuts and additions, it could all have gone so horribly wrong. Make too many changes and you infuriate one of the largest and most devout fanbases in all of gaming. Make too few changes and you risk releasing a game that's accused of being stale. Frumpy. Old-fashioned.
But it didn't, and you're thankfully left with a game that keeps the spirit of Civilization alive with one hand, while with the other, it casts aside twenty years of mechanical dead weight in favour of a faster, cleaner and more enjoyable game.