Finally units like archers arenīt just another type of melee unit that just gets different boni, but can do real ranged attacks (making them extremly powerful, especially if accompanied by melee units).
This definitely gives more strategic depth to the combat system :b:
This new system makes it worthwhile to generate extra happiness! The happier you citizen are, the sooner a Golden age will arrive. This gives extra dept to happiness, and it's a lot more realistic, let's be honest, which Great Person in history did ever start a Golden Age himself?
With civ5 money finally has value! No longer is money only a negotiation tool till 'Democracy'. One can use money to purchase buildings and units, bribe city states and buy tiles! It now pays of to save money and there are several choices to make when you want to spend your money.
Finally we are forced to not road every single tile on the map, simply because it costs money. Resources are connected without roads. Roads are there simply for movement, not for the sake of giving your worker a job to do.
If not only for introducing a complete new combat system, Civ5 deserves our praise! After 4 games of more or less similar combat, the game has now innovated itself on one of the core aspects of the game. 1UPT makes the positioning of troops a lot more important. War is becoming a lot more strategical.
Purchase buildings and units while producing other buildings and units
(discuss this item)
Another new element of civ5 is that you can use gold to purchase stuff that you're not working on yet! Units right out of the box. No need to temporarily abandon to work on your wonder, use money to build an army as well while the wonder production (etc.) won't be delayed!
With previous Civ iterations it often felt like one was more managing a bunch of cities then an empire. Every city needed care in itself. Happiness, health, culture. Only the civics of civ4 were more focused on your entire Empire. Now with Civilization V there are more mechanics to give the empire feeling. Unhappiness, culture, social policies, golden ages... they all depend on how you run your empire. Even tiles can often be bought by several cities. And there's more. That's a good change!
City States are a huge innovation! It makes diplomacy more interesting and finally the Diplomatic Victory is interesting! New decisions to make! Will I let them live or will I incorporate them into my empire? And what to do when my friends, the Russians, invade my allied City State?
Civilization 5 offers a big number of possible buildings for each city. It is impossible to build them all in all your cities. More then any Civ game before. There are many more choices to make now. This helps to specialize cities.
The new system where happiness is calculated for your entire empire reduces micromanagement and makes the game feel more like an empire-building game then a 'manager a bunch of individual cities' game. Now you can specialize cities for building ie. happiness buildings while your military cities continue to produce units without interruption.
In previous civ games intercontinental warfare was rare. It took way too much time to get huge armies across an ocean, it was too expensive and required to much coordination and planning. With embarking in this is all gone! We can have inter continental wars, and having naval forces is finally important as well.
In civ4 the 'cottages' were invented. A tile improvement which value would crow over time. The longer your city worked the cottage, the more commerce output it generated. It was an important decision early on. Perhaps a tile would on the short term generate less, but on the long term it will pay off. Trading posts do generate more money over time as well because of new techs an policies, but they don't need to mature. Just build farms early and replace them with TPs later. Is that good?
Steam is good, it's easier to play MP (no need to login on Gamespy), you get the latest patches automatically, you can play on multiple computers, taking your savegames with you, it comes with enourmous good community options b/c of the groups! (all join the Apolyton steam group!)