I was very worried about what I was reading here as I lurked, so I waited for the patch before buying the game. I installed the game and then the patch, so I never attempted to play without the patch. My system is a 20" iMac G5 2.1GHz 1.5Gb running X.4.7.
I ran one game through to about 2000 on a small world, full screen. It slowed in the more modern era, but not too badly. I had a few game crash problems, but in my second game, I finally figured out how to make the game run in a window, and I don't think I've had a crash since (though I'm not that far into my second game). OTOH, running in a window, I find it harder (impossible?) to scroll the map when, say, telling a unit to goto someplace off the current screen. In fullscreen, mousing to the edge made the map scroll, but now the mouse just goes off the window.
I'm not sure what the game's *supposed* to sound like, but I seem to have continuous music (the only exception I can think of is when a game is loading, the music will cut out for a second when the load bar is about 75% done) and it plays a reasonable amount of ambient sound effects (cheers, etc.). No combat sound, and combat animation is jerky.
The only other weird thing I've noticed that I haven't seen mentioned was that at one point all the cities and improvements on the world map turned black. After saving and restarting, it was okay again.
I'm still learning the ropes of the game, so I'm not yet too concerned about the occasional crash and glitch. With the patch, I find the game playable and enjoyable, but I hope and trust more fixes will come in the future. Thanks to Aspyr for addressing problems quickly.