What amazes me is that despite of what people said about cIV being very divisive and disappointing during release (which I could find little to no evidence of in the forum archives) the game at the moment holds the lowest vote count for being the worst in the series w/o expansions.
The fact is, most people saying that Civ4's launch was comparable to Civ5 are, simply put, blind fanboys. They are the same that caricature the issues with Civ5 as being about "people who just complain because it's not Civ4" and the like. Don't put much stock in what they say.
Civ4 had a lot of troubles bug-wise, and there was definitely lots of complaints about the bugs, crashes and the like, but it was nevertheless celebrated for its gameplay right at the start. Most everyone said "it's buggy, but the game is great".
And I was part of the people who had a hard time getting into it, so it's not like I didn't see it from the most unfavourable point of view. Still, it was plainly obvious that the mechanics were very fine-tuned and the concepts sound.
Wow, I never realized there was so much dislike for CivIII. I've seen it more and more lately, seemingly out of the blue. Somethings tells me it's a lot of those people who started with Civ4, and then tried CivIII.
Civ 3 had a LOT of holes in its design.
Corruption was insane and made getting cities rather pointless.
Diplomacy was completely broken (either you exploited it, playing the broker, and it was overpowered ; either you didn't exploit it and it was simply totally useless, the AI always wanting several times more than what they accepted to give).
Many concepts were badly implemented (the quoted "you have a stack of units in a city, it suddendly revolt and your stack vanish").
The ending was a joke (the same as Civ5 : just a pop-up saying "you win !", save for the Space Race that had a little movie).
No wonder movies.
It was very unpolished - especially gameplay/design-wise - at release. Many people compared it unfavourably to Civ2, and it was rather divisive of the community.
But unlike Civ5, it had a lot of saving graces that made it a worthy addition to the serie : it was very immersive (the whole interface was very neatly designed to drawn you into the game) and more than anything, it made the franchise go forward, adding new concepts that were so integral to the game that it made going backward very difficult - the whole culture and borders thing, units maintenance based on gold drawn from the whole budget rather than the weird "shield from home city" and the like.