I happened to write a very long post (bordering on essay) on this very subject last night, but then I made the mistake of previewing it, which accidentally lost me the whole text! 
I feel safe to comment on this because as it happens I've liked all the Civ games so far (the proper ones, didn't like CtP), plus I even enjoyed Colonization very much
I agree very much with what people are saying about Civ2, and I see it's about the same that I wrote about it last night; Howitzers, super-wonders, crazy rail-roading terraforming engineers, etc etc, Civ2 was, in the end, too *wild*. There was too much power available to the smart player which the AI would never think of using, let alone exploiting. Civ2 was very fun to play, until you'd milked it dry in Deity, as most of us did.
What kept Civ2 going so long was indeed the scenarios and customizability; and let no-one say I'm not qualified to pass my judgement, I played Civ2 thousands of times in all kinds of ways (including dozens of scenarios) and spent a lot of time creating scenarios too (complete with units sprites etc).
As to Civ3, I'm pleased with it, on the whole. Most of the new concepts are very good additions to the genre, most notably culture, resources, civ attributes and UU's, and the Golden Age. I also like bombardment and the improved diplomacy. The AI is a lot better at fighting its wars now, *compared to Civ2*. I also praise Firaxis for balancing the wonders and the settlers.
I dislike the tech tree though, especially the modern age (why can you build nuclear subs when you still don't know about nuclear weapons, and why can you get the tech for Modern Armor without knowing about Aluminium? It's flimsy). And as stated over and over, there are bugs and the interface has many flaws. Also the orange blobs known as pollution are not adding much fun to my games, au contraire!
Okay, I've pretty much said what everyone is saying, but I wanted to make one point:
In my own personal case, I got Civ2 without having anticipated it for a long time. It was like a surprise gift from Heaven! So I was too happy to be critical of it from the start. But I had known about Civ3 since 1999, and spent much time on forums debating the wish list for it. All that anticipation was bound to end in some disappointment, once I'd face the real Civ3, as it did. Of course Civ3 wasn't everything I'd hoped for, far from it, and of course it couldn't recreate the magic of Civ1, back in the old days. I don't think any Civ sequel ever will.
I don't know if others experienced the same, but think about it; did you have the same expectations for Civ2, the same long period ending in inevitable disappointment?

I feel safe to comment on this because as it happens I've liked all the Civ games so far (the proper ones, didn't like CtP), plus I even enjoyed Colonization very much

I agree very much with what people are saying about Civ2, and I see it's about the same that I wrote about it last night; Howitzers, super-wonders, crazy rail-roading terraforming engineers, etc etc, Civ2 was, in the end, too *wild*. There was too much power available to the smart player which the AI would never think of using, let alone exploiting. Civ2 was very fun to play, until you'd milked it dry in Deity, as most of us did.
What kept Civ2 going so long was indeed the scenarios and customizability; and let no-one say I'm not qualified to pass my judgement, I played Civ2 thousands of times in all kinds of ways (including dozens of scenarios) and spent a lot of time creating scenarios too (complete with units sprites etc).
As to Civ3, I'm pleased with it, on the whole. Most of the new concepts are very good additions to the genre, most notably culture, resources, civ attributes and UU's, and the Golden Age. I also like bombardment and the improved diplomacy. The AI is a lot better at fighting its wars now, *compared to Civ2*. I also praise Firaxis for balancing the wonders and the settlers.
I dislike the tech tree though, especially the modern age (why can you build nuclear subs when you still don't know about nuclear weapons, and why can you get the tech for Modern Armor without knowing about Aluminium? It's flimsy). And as stated over and over, there are bugs and the interface has many flaws. Also the orange blobs known as pollution are not adding much fun to my games, au contraire!
Okay, I've pretty much said what everyone is saying, but I wanted to make one point:
In my own personal case, I got Civ2 without having anticipated it for a long time. It was like a surprise gift from Heaven! So I was too happy to be critical of it from the start. But I had known about Civ3 since 1999, and spent much time on forums debating the wish list for it. All that anticipation was bound to end in some disappointment, once I'd face the real Civ3, as it did. Of course Civ3 wasn't everything I'd hoped for, far from it, and of course it couldn't recreate the magic of Civ1, back in the old days. I don't think any Civ sequel ever will.
I don't know if others experienced the same, but think about it; did you have the same expectations for Civ2, the same long period ending in inevitable disappointment?