Civ 3 Play the World has good ideas, but lousy implementation
The new gameplay modes have potential. I liked how Elimination made it possible to finish a game in 40 minutes.
Some of the new civilizations are interesting too. Most of them have a big emphasis on early military conquest, and some of the Ancient Era units seem too powerful to me (like the Celtic swordsmen) or they seem to negate other special units. For example, the Numidean Spearmen have attack 2 defense 3, and the Greek Phalanx has attack 1 defense 3 and is slightly cheaper. Which would you rather have?
The main problem with the game is that there is so much lag during internet play that the game is unplayable. Shame on Firaxis and Infogrames for releasing their game in this condition. The first night I got it I successfully joined about 3 games out of 10 and 1 of those games crapped out early due to lag issues. The lag is not helped by having essentially two login screens for a game when there could be just one. The first login screen doesn't even let you kick lagging players, so you have to remake the entire game if someone refuses to leave or crashes. The second login screen with the detailed information does let you kick players, but if a player crashes it often doesn't drop them correctly, forcing you to remake the game.
The new gameplay modes really aren't all that great. I liked Elimination for the quickness of the game, but that mode gets old pretty fast. Regicide and Mass Regicide sound cool, but there is no reason to not put all your kings in your capital unless you are playing in the modern era where they could all be nuked. I was disappointed that there were no gameplay modes for cultural or economic victory conditions. "Amass xxx culture points/gold" would have been an interesting variation over all of the military victory scenarios that we get by default.
Finally, the bundled scenarios and maps are of low quality. Several maps don't even have any strategic resources on them or other glaring errors. I also noticed that the scenarios tended to be on huge maps, which are no fun even on a fast computer because the computer takes forever to play its turns. I would have liked to see more small maps and more custom scenarios designed for 1 or 2 hour multiplayer games.
The Bottom Line
Civilization 3: Play the World fails in two ways: it doesn't offer enough new gameplay features to be a worthwhile single-player expansion, and its multiplayer games are currently unplayable, leaving you with not much for your money.