The graphics haven't changed since 2005, the art assets on the naval vessels are the same, and despite an excellent soundtrack of Native American chants and light classical music, the whole thing is more Civilization IV expansion than "Colonization 2". If you loved Civ4 that's not a problem, but this game is purely for the fans - if you didn't care much for Civ4 the first time around, Colonization isn't going to change your mind.
Bottom Line: The more things change, the more they stay the same. Sid Meier's Civilization IV: Colonization is a game for hardcore Civilization fans only.
Recommendation: If you're a fan of the series and the genre and can get over the fact that you are, in essence, paying for a very well polished, Civ4 mod, this will be the best thirty bucks you will spend this holiday season. Otherwise, give it a miss.