I have no doubts that this is the best entry in the Civilization series (6 has been released at the time of writing). That being said, this game is heavily contingent on key expansions in order to be a complete experience, and even then the balance and pacing of the game is completely off.

Now, in 2021, the game has been heavily visited and re-visited by a highly proactive modding community who have attempted time and time again to "fix" the game in a competitive sense to make it more engaging. I deeply respect the efforts of those who worked on this project, basically doing unpaid labor for the original developers. That being said, the result of their project- to me anyway- was the revelation that the game was simply unsalvageable.

The game takes forever to play, even on a fast pace. This wouldn't be a problem if it weren't for the fact that the match is decided relatively definitively by a few small details, and the vast majority of this time is spent on busywork and tedious micromanagement contingent on uninteresting game knowledge which must be painstakingly built up over a long period of time, sapping the critical decision making process out of the game. This issue is compounded by the fact that the spectrum of different skills among players is so massive as to sour the experience for matches among friends who haven't already sunk many days of their life learning and practicing.

The singleplayer experience is not fun at all. The AI, even on the hardest difficulty, is ludicrously easy to beat and never produces interesting situations. It might be good for a power trip, but that's about it.