If you love CIV IV, you will most likely hate CIV 5, here's why:
Absurdly Lacking MP Support
No improvements at all from CIV IV: No dedicated servers, no matchmaking, constant lag issue, framerate problems, no online ladder and rankings, no unit animation, random crashes, no way of reconnecting a game, no way of joining a mid-game through invite.
No reason to play MP at all.
Don't care, I never play MP. I've got too much to do to devote that much time to one sitting.
No SP Scenario
SP consists only of "Play Now" and "Custom Game". It doesn't get any more plain than this. And it has the stench of "sloth" and "greed" all over it.
Don't care - I never play scenarios.
No Tile Animation
Why the **** is this taken out? Why must players have to go into the city menu to see what tiles are being worked on??
This I agree with. Though I don't care so much about animation, but I definitely would like a way to know which tiles are being worked without having to go into the city screen. Probably my biggest beef with the UI.
No Religions
Religions weren't necessary, but it added flavors to the game. It was awesome trying to spread your state religion to the whole world, earning diplomatic favors and gold in the process. CIV IV lovers want the religion system to enhance so that it can impact the game in a more meaningful way, not remove it entirely.
Religions were
okay in Civ4, but that system doesn't seem like it'd fit in Civ5 (mostly because of city states). City States are much better at stirring things up between the major Civs in a meaningful way pertaining to the current game. Religions were basically arbitrary.
No Espionage
Espionage was one of the best features to have been introduced in the CIV series. It gave players so many options and alternatives to go against their opponents without the risks of declaring open war: poison their water supply, scout out enemy troop strength, stir up a rebellion, steal their treasury, sabotage their wonder construction, etc. Why is this awesome feature removed completely?
Gawd I HATED espionage in BTS. HATED IT. Glad it's gone, and if it ever returns I seriously hope it's in a completely different form (or I have the ability to disable it).
No Civics
Civics was another extremely well-thought out feature that was added in CIV IV. Not only did it add flavors to each nation (Communism vs. Capitalism, Emancipation vs. Slavery, Universal Suffrage vs. Police State), it provides long term tactical options as well as short term flexibility to players to adapt their empires based on the current circumstance. Deciding and changing Civics was always a weighty decision because each one of them have their pros and cons. It makes each nation unique because rarely do two empires have the identical set of Civics.
In CIV 5 Civics are replaced by Social Policies, which is fundamentally a ladder of perks with bonuses that you can upgrade one at a time. It may still be strategic to decide on which branch of policies and perk to upgrade, but because of the fact that they are permanent and you cannot change them, they offer absolutely no tactical flexibility to players. All branches and perks add some kind of bonus to your empire with no negative side effects, so the decision of choosing which one to upgrade also becomes less significant.
SP's >>>>> Civics. If Civ4 had SP's and Civ5 had Civics, then I'd actually agree that something significant in Civ5 was dumbed-down. But since it's going the other way, the depth in terms of framing your cultural heritage and society has increased by a lot.
No Hamlets
Hamlets was an important tile improvement in CIV IV as the primary commerce provider. But its greatest strength is that over time it evolves into a cottage, a village and ultimately a town, encouraging players to build them early to reap the benefits.
In CIV 5 hamlet is replaced by "trading post" which has a MUCH uglier model and does not evolve.
At first I would have agreed. But after playing a few games of Civ5, (Trading Post graphics aside) I think that the way TP's work fits much better into the economic system of Civ5, and Cottages->Towns would have been overpowered. And I'm also happy to see the one-size-fits-all CE go bye bye too.
No World Wonder Movies
Now all we get is a still picture and some quotes that most people don't give a **** about.
Meh. I watch 'em once and then click through after that.
No End Game Cinematics
Players sit through 10 hours to beat the game and you can't even make a 10 second animation to reward and congratulate them?
Meh again.
No Commerce, Research and Culture Sliders
Commerce, Research and Culture used to be interlinked in building your empire. Any of these resources can be distributed freely using sliders to let players develop their nations in the exact way they want.
In CIV 5, commerce, research and culture are completely separate entities. And the only decision players can make is to decide how much of each resource to produce.
Again, like SP's, here's another place where Civ5 is the opposite of being dumbed-down. It's being "smarted-up", because you actually have to manage your economy, production, research, etc. You don't have the safety net of "oh I'm losing money, time to set the slider to 0!"
No Random Events
Random events provide small bonuses and surprises to your nation in the way of additional income, one additional food resource, increased culture, etc. Those bonuses are no way game-breaking, but they make you smile every now and then and make your empire feel like a real nation inhabited by living breathing people rather than some numbers and data on the screen.
Good riddance!
User Interface
Firaxis might have thought that they were very clever in making the UI much more streamlined and linear, but it is NOT! This type of UI may have been ideal for the console version of Civ because of the limitation of the controller, but for a PC CIV this kind of UI brings more inconvenience and frustrations than otherwise.
PC gamers want data and information easily accessible, laid out clearly right in front of them, instead of clicking through menus and menus before finding out what they want to know.
For the most part, I think Civ 5's UI blows away Civ 4's UI. There are a couple of (patchable) quirks, but it's much cleaner and efficient. People who say Civ5 isn't a deep game have not yet figured out the UI, because the vast majority of information and detail is there, it's just not on a cluttered screen.
City States
I really question the point of implementing City States. It may be fun to interact with them and build a good diplomatic relationship with them, but more often than not it's much easier, simpler and faster to just conquer them and take their resources than to waste gold buying their friendship.
The importance of City States as allies in war times is extremely limited too, considering that now military units cannot stack, and City States have such a small territory, their army size and strength naturally become very restricted.
I saw your post saying you'd look at CS's more closely, so let me say that I think CS's are brilliant! Play as Greece and complete the Patronage tree, and you'll see.
Framerate Problems
Even on Medium settings, and according to the requirements of the game my PC is more than enough to handle this game on High. It's painfully obvious that this game wasn't optimized.
I'm below the recommended specs, but am running the game on max-everything graphics with a smooth framerate. No crashes, either.
No Leader Personality Traits
It provides a historical and semi-realistic flavors to each leader. And although some traits provokes controversies and debates amongst historians for their accuracy, it's part of the fun too.
Leader traits == Civ Special Abilities. Which are unique this time, instead of a combo of 2 bonuses. Both systems are cool with me.
One Leader Per Nation
Is it really that much to ask for to have at least two leaders, even for a Vanilla pack?
So far. The UI still does have a spot for the Civ and a spot for the leader, so the door still seems to be open for multi-leader civs.
What CIV 5 managed to do right:
I agree with all of this.
Overall Conclusion: If you are a CIV IV fan, you will most likely hate this atrocity of a "sequel". Sequel, by definition, is supposed to improve on the original by fixing predecessor's flaws and enhance its strengths. But ironically CIV 5 has actually completely removed some of the strengths that made CIV IV so enjoyable, instead of building upon them and perfecting them. When counting the merits of the game from the aforementioned list, CIV 5's failings evidently outnumber its qualities by a staggering margin.
I LOVE Civ 4 BTS. In fact, it's my favorite game ever. But I think that before long I'll have to say Civ5 is better. I already think so, but it's still too early to say definitively.