
If you like Civilization Colonization it will offer a huge amount of replay value in both the single player and multiplayer arenas. With up to four player multiplayer the matches can be very long and fun if you are playing with people who know the game.
Bottom Line:
If you are a big fan of Civilization IV you probably will enjoy Colonization even though it feels like a rushed attempt at expanding Civilization IV. Only buy if you are a serious fan of the series and Civilization IV is no longer enticing you to play.

2K will implement online service changes for several legacy titles, including releases for Windows PC, as a result of GameSpy Technology terminating its online service offerings for video games.
Beginning May 31, 2014, select legacy titles from the Borderlands® and Civilization® catalogs will temporarily go offline while service is transitioned to Steamworks.

GamerDeals.net:
"75% OFF Civilization Weekend Sale!
Amazon has kicked off a Weekend Civilization Sale!
From now until Sunday, get 75% off Civilization IV and Civilization V games and expansion packs. That means Civ IV is $4.99, Civ IV Complete Edition (both Steam and no-DRM versions) and Civ V for $7.49, Civ V Complete Edition for $12.49, and DLC as low as $0.75."

GameFront, "In an age when even old-school FPS gurus like iD’s John Carmack are defecting to consoles, you can still be sure of one thing: strategy gaming has ever been and will always be the province of PC’s. Whether it’s due to the more cerebral, measured gameplay, or — more likely — the crucial importance of mouse controls, the jump to other platforms is rarely successful. Despite their large market share and stable, unchanging hardware, consoles struggle to sustain a pure strategy game."
I pretty much clicked on this to ensure that Homeworld was included and sure enough it is. I approve.
Damn it I want to play Homeworld. Why hasn't Relic got it up on a digital distribution service like Steam?!