I gave it a good shot so far. After playing about 50hrs with it I have to say that the extra units, civilizations, wonders and improvements do make a big improvement in the gameplay. Civ3 was already a great strategy game and the expansion is making it somewhat better BUT:
1) The big selling point from that expansion is the multiplayer feature...and it doesn't even work! How can a great name like Firaxis let something like that happen? Of course it can be fixed with a patch but I pay premium price to have this game now and I want it to be playable now. The lag in multiplayer (through gamespy) is atrocious and don't even think about playing a whole game without being disconnected at least once!
2) It's a big expensive patch that should have never come out the way it is. Shame on Firaxis for letter it happens and shame on the tester for letter major bugs slip in.
My score of 5/10 reflect al this. There's some gameplay improvement, but the main feature is non-functional.