Older players will enjoy the nostalgic value, but as a 2008 release Colonization is sorely lacking.
It's really a mystery why it took so long, but sadly the result was not worth the wait. Veterans of the original will be able to pick up where they left off in the mid 90'ties, because almost nothing has changed but the graphics.
There have been made some very minor improvements to trade routes, the implementation of a new kind of colonist and the addition of governments. Most of these are superficial afterthoughts, and the overall impression is that of a hack copy / paste job with some better graphics.
The UI is terrible, the difficulty completely out of whack, the AI very poor, and there's very little replay value. Colonization is also plagued with lazy bugs, that were forgivable in 1994, but frankly don't belong in a 2008 release.
It's possible (and you really should) to wipe out the three other nations within 10-20 turns of the game just using your starting soldier. The King will continue to demand higher taxes - even when it's already at the capped 99%.
The game is also rediculously hard. I've played about 10 games so far on the second easiest setting, and not once have I come close to winning. The Kings expeditionary forces usually outnumber your colonist 4 to 1.
It's certainly not impossible to win, but it requires you amass a force of hundreds of soldiers of your own, which feels like pointless busywork.
The overall impression of Sid Meiers Civilization 4: Colonization is that of a soulless cashgrab much like the remake of Pirates! It's only $30 though, which may be worth it for nostalgic reasons alone. Players unfamiliar with Colonization should stay clear however.