Like many (err probably all) of you, Civ 4 is not working well on my Macs.
I agree with Wiglaff that if Aspyr "aspires" to sell a game that it should be playable.
In my opinion, civ 4 is not playable on my iMac g5 but it is playable on my Intel Macbook pro. In this regard the system requirements are probably misleading.
On the other side of the coin, I think it is critically important to support efforts to port games to the mac.
I, for one, am grateful for the efforts of Brad and Aspyr to port games to the mac.
I have a strong suspicion that the codebase for Civ is difficult to port. The fact that they developed with Direct X instead of OpenGL, or used proprietary Microsoft XML librariesis indicates a total disregard of portability. It is very unfortunate that Firaxis failed to utilize developers with some notion of platform portability. If you design for portability from the start, it is not nearly as expensive as if you ignore it completely.
Realizing that there is no way Brad could ever publicly comment on the code quality, we must give him the benefit of the doubt.
It may well be that the choice is either have a buggy, non-performing port or nothing at all.
In that case, I still prefer a slow, buggy $50 port rather than nothing.
Now I will return to playing Civ 4.....on the PC ;-)