* The revamped interface allows both new and old players to spend less time figuring out how to manage their empire and more time getting stuff done
* Fewer, more robust units make per-turn unit management quicker
* The changes implemented in the combat system present interesting new challenges and advantages to both offense and defense
* City-states are a great addition to the game in terms of resources, combat, and diplomacy. For Civ4 vets, they are vassals writ large
* The graphics are very pretty and not terribly demanding on the system; the settings have a good deal of flexibility
* The "quests" lend some micro-structure to the game, something to do between wars or when no one likes you enough to trade
* I have not yet seen them, but I've heard that in the modern era you can build Tiny Death Robots
* It's still addictive as hell, and sweeps you into the action immediately, every time, without overwhelming you
* The AI has been reworked, but diplomatic relations with them occasionally have an overtone of "if you don't know what's wrong, I'm not going to tell you"
* Some parts are a little goofy. I had no problem with the lists when they were "The Happiest Civilizations," as opposed to now, where it's "People that Smile the Most"
* Social policies and culture are almost forgettable if you're more into domination/conquest/diplomatic victories
* No technology trading, which was marginally more realistic than a "research agreement," at least in the BC years, and less expensive
* Alerts can stack up and it can be tiresome to dismiss a huge pile of them just make sure you've dealt with them all
* Hardcore fans may not agree with some of the editing choices made in the streamlining of the game, and may feel that victory doesn't require exactly the same grueling tenacity
* The purchasing aspects of the game (units, buildings, tiles, influence, research agreements) may come to feel like or be perceived as cheesy strategy, especially in multiplayer games, since you mostly just have to know how to generate money