The game is riddle with all sorts of minor bugs that don't nescesserly destroy the experiance, but obviously need patching. Many people have experianced moderate bugs like graphical glitches, slowness and desktop drops. Many of these types of issues can be avoided if your willing to do a clean format and XP install. Some people have reported severe virus like bugs that caused severe software failures and blue screens of death after installing the game, these are a bit more rare but I found at least 15-20 people that had these types of problems.
Outside of technical issues with video cards, obvious miscalculation of minimum requirements, miss labeled CDs, at least 30-40 minor in game bugs or oversights and of course the chance that the game will completetly crash your game, it's actually a good game if you can believe. In fact, I would easily say it's the best CIV game ever made if I wasn't unlucky enough to be one of the hundreds of people experiancing technical problems. In my case I can't load saved games, which I suppose isn't nearly as bad as some of the problems people are having but it definitly takes away from the experiance.
On the bright side, strangly enough the multiplayer is actually more stable and has less bugs then the single player game, obviously the result of Q and A testing focus.
Should you buy the game? Depends on your personal deamenor, I rushed out even after being warned of the countless bugs and technical issues and have spent the last week frustrated over a stupid game. I don't regret buying it, but I'm anxiously awaiting a patch that will hopefully fix my tech problems.