Civ 4 is hideously ugly. When I first tried it, I had to check my hardware because there was no way the leaderheads could actually be so much worse than Civ 3. It achieved a rare state of having terrible unit graphics on vomitous terrain, surrounded by an atrocious interface that is slathered with useless information. This is before you check the city and are treated to yuck faces, minecraft hammers, and a claustrophobic display that makes you feel like you are in Buffalo Bill's dungeon. Let's not forget the amazing Civilopedia: as Civinator described it is filled with nonsense and has children's illustrations in tiny boxes. I enjoy such classics as this guy, who looks distraught because Dr. Venkman gave him too many shocks.
Or the incredible attention to detail on the wonders that blows away civ 3.
Ok, maybe it's an ugly duckling but inside inside a beautiful swan is waiting to come out. Civ 4 did add some new features which I enjoyed. I liked the idea of policies that you could change, although I thought they would have worked better in conjunction with governments instead of in place of them. The addition of resource-specific on-the-map tile improvements was a good feature. Rolling over production was fine. The health feature was a tolerable alternative to pollution. And everybody likes Nimoy. Some of these features, however, were a double-edged sword. Religions were a good idea, but their implementation was clunky. There was too much emphasis on the bonuses that come with founding a religion, and the evangelical mechanics are raw. Diplomacy got an upgrade from Civ III but still left much to be desired. And many minor details detracted from the game.
My biggest beefs with the game are the atrocious city-founding mechanics that were intended to limit expansion, the horrendous combat that made me avoid wars at all costs, and the old trap of thinking that more content equals more strategic choice. First, the cities. The manual explains how they wanted to get away from the huge empires of the early games, and find a replacement for the corruption system. Fine, ok, got it. So their plan was to make it so every new city you create sends your treasury into the ditch. Founding religions and other distractions are necessary just to have enough money to create more cities. Remember in history when nomadic peoples wanted to move to new regions with better resources, but couldn't because their treasury was running low? So the series went from "100 cities is a bit much" to "Five cities will crash your economy". Forget trying to compete for contentious middle ground. Never mind early wars and seizing critical areas. Remember in history when Alexander was like, "I'd like to conquer the known world, but our treasury is running low and only 16 more turns to Ceremonial Burial"?
So the King of Fun took our expansion phase away, and then gave us the most ignorant combat system imaginable. Nothing like ancient catapults that launch DPICM submunitions and weaken whole stacks of "Axemen". Better get those winged horsemen to ride 'round the Anglish and FLANK them. Rock, paper, scissors sucks and everyone over age 7 knows this. So, the big plan to remove stacks of doom instead gave us stacks of Macemen with redundant and pointless promotions, wandering all over creation. Don't forget exciting new additions like the SAM missileer, and the stealth destroyer! I never wanted Civ to be a wargame, but neither did I want it to be a goofy circus.
Third is the plethora of nonsense infused in the game. Endless buildings and wonders await you, most without purpose or meaning. You're supposed to pick and choose, according to Firaxis, but instead of coming up with a nice system of specialization (even a simplified one like in Total War), you instead have to wade through piles of trash to see what to build. This can be added to byzantine labyrinth of the tech tree, which looks like a flow chart for dealing with a nuclear meltdown. This is just my preference, but the game made the decision to allow multiple paths and the ability to skip around the tree. They deliberately wanted to blur the lines between eras, which is the opposite of what I was looking for in the series. This approach worked nicely in Civ Revolution because that's a casual game. But in the main series it makes history into a soup sandwich. Sometimes I would discover riflemen only to realize that I had skipped musketmen and about 300 years of development. Half the trash in the tree never got used, because it was useless. Instead of the tech tree propelling the narrative of the game, it felt like a morass that even Nimoy couldn't save.
The end result was a game that was an endless, frustrating slog. It was ugly, and irritating, and unrewarding. The music sucks. Using disconnected classical music is not good game design, and the post-modern discomfort music makes you want to end the nightmare as soon as possible. The game fails to communicate critical information clearly and effectively. That's one area I really enjoyed in Civ 5, where the care given to the gorgeous interface and music helped move the game along. Better than trying Civ 4 diplomacy with plenty of options to make sure you don't miss any important details!