Having just reviewed Beyond the Sword, the latest expansion for Civ4, website Driver Heaven had this to say:
"Big games deserve big expansions. Blizzard know this, and apparently so do Firaxis. Warlords brought new things to the table and refined the original formula. Beyond the Sword doesn’t settle with that. It delivers enough new content to dwarf stand alone games and makes some drastic changes to the way the game is played, making this more of a Civilization IV.5 than just an expansion. With months-worth of new scenarios, refinements done to the core gameplay and a ton of polished applied to the engine this expansion is just amazing. If you have Civ 4 you must buy it. If not, you must buy Civ 4 just so that you can buy the expansion as well!"