I keep thinking "Civ: Call to Power," which may be an even worse insult. It feels like an imposter. It baby-fies things that really worked, like the tech slider, happiness, and health, and then adds complications that have nothing much to do with the underlying game.
If you take out the 1upt change, what are you left with?
1. New map and border style. It's very nice; I'd even call it massive step forward as far as immersiveness, because it makes boundaries and borders and geographical features much more organic looking. I've been wanting an "expand by only one tile" feature since Civ I, and I can't tell you what a relief I feel to finally have it. But by itself, these do not justify a "V" in the series.
2. Radical simplification of empire management. Civ IV finally found the balance between builder/quality and expansion/quantity strategies. You had to expand to get resources, but you were sharply limited by costs until the late stages when for sound economic, social, and technological reasons large political units become viable. In the meantime you had to gin up super-efficient small empire because the world wouldn't go away just because you had to stay small. You had custom-craft each city for production, research, culture, Wonders, etc., and you had lots of viable strategies to choose from--Wonder economies, specialist economies, cottage economies, etc. It was a long and steep learning curve, but worth it. CiV? Well, I have to play around with it some more, but an empire-wide cap on happiness is a far cruder way of imposing early game limits. The lack of city-specific health and happiness bottlenecks takes away one of the environmental shapers that forced you to custom-craft a city to minimize its weaknesses while trying to build to its geographical strengths. "Cottages" (now trading posts) do not evolve. I feel like I've had a superbly made toolbox taken from me and gotten "Baby's First Hammer and Screwdriver" as a replacement.
3. Diplomacy: You can do research pacts, which substitute for tech trading. That's a step back, both in complexity and immersion. Open borders? No change. Resource trading? No change. Map trading, civics, religion? Gone. The deletion of map-trading is especially irksome. That's like an FU move on the designer's part. "Let's take out something people like and want for absolutely no good reason, just so they know who's the boss in this relationship." New stuff? You can sign "Pacts of Cooperation" or "Pacts of Secrecy" which do ... No one knows. There's no documentation on them. You can't tell how or why someone is pissed at or pleased with you. Foreign leaders will pop up with these gnomic, passive-aggressive declarations ("It's a shame that the world is full of people who pick on those who are weaker than them") and you're supposed to reply either "Very well" or "You'll pay for that." I want a button that says "Oooooooohhhhkay. Moving on ..." Diplomacy in Civ I made more sense.
City-states are a subdivision of diplomacy. They deserve more study before getting a final judgment, but my first impression is that they and their quests lack variety. It's funny: they have more detail and fit in more complexly than the independent cities in RFC, but they actually feel blander for it. It's a paradox, but it sometimes happens ...
4. Social Policies: Civics, treated like a tech tree. It might be a good advance after you play with it and figure it out some more, but it feels like a wash.
5. Bells and whistles: Animated leaders look nice, but they have about 1% of the personality of the leaderheads in Civ IV. Did you love it when Catherine slapped you? Did you LOL at some of those faces that Alexander (the CivIV original, not the RFC modification) pulled? In CiV they stand in a garden and look at the birds and drop these diplomatic koans, and I'm the one who's left screaming in frustration like Pacal.
Wonder movies--to be fair, how were they going to improve on those in CivIV? But the "movies" here feel like they decided to not even compete. Since they carried over sound effects from Civ IV, why not carry over the movies? Soundtrack--I gather this is now civ-specific, not era-specific, but the soundtracks for the Persians and Aztecs, at least, are generic faux-tribal wallpaper. And I like my music to evolve along with my tech. It's an aural reward for doing well.
So ... a new map style that is very good. The bulk is unchanged or significantly degraded. That leaves the combat system as the only really new thing, and it breaks immersion and feels like it was put in by a designer who was itching to play Panzer General and wanted to force us to play it too.