Call to Power II is definitely a superior game to Civilization: Call to Power, which should be enough to recommend it to those players who did enjoy the previous game.
The original Civilization: Call to Power was supposed to be a sort of sequel to Sid Meier's Civilization II - even though its game system was clearly based on Sid Meier's legendary design, it tried to extend and improve the basic concepts. Unfortunately, it wasn't particularly successful. Eighteen months later, Activision has taken another crack at reinterpreting the classic empire-building game. The result is stripped of the Civilization name (for licensing reasons, since Hasbro actually owns the name) and simply titled Call to Power II, and it's an improved - if still flawed - computer game.
In many ways, Call to Power II is what Activision probably meant the first Call to Power to be. Many people abandoned the first one due to its clumsy interface, which seemed to defy all logic and convention. Apparently, Activision took those users' complaints to heart, because the interface in Call to Power II is tremendously improved. The dialog boxes are better organized, buttons can be moved easily between the various summary screens, and everything is much more intuitively laid out. Therefore, unlike in the first game, those players with even a passing acquaintance with the Civilization concept will be able to jump into Call to Power II without much trouble. That's a significant improvement over the original Call to Power.
The graphics have also been given an overhaul, and while they are almost identical in style to those in Call to Power, they've been cleaned up - so now, they look very attractive. In addition, the animations and many of the sounds are extremely well done. Visually, Call to Power II is excellent.
One of the biggest changes to the Civilization system in the original Call to Power was the removal of some of the city-specific micromanagement, which was intrinsic to the whole Civilization concept. Instead of clicking through every city to adjust whether an individual worker was on a grassland or a plains tile, Call to Power introduced the concept of "public works." You'd designate a certain percentage of an empire's tax income to go to public works, and you'd use this pool of cash to construct tile improvements. These tile improvements can be made to any tile within a city's sphere of influence, and they don't require a specific worker to use them. Instead, a city reaps the benefits of tile improvements as a function of population size.
This somewhat more large-scale adjustment is a definite design aim of the Call to Power series. Most empire-building games focus heavily on micromanagement, and they have dozens of individual factors that need to be taken into account. Call to Power II streamlines this by eliminating other things, like individual city support for military units. The diplomacy system has been revamped as well, and at first glance, it's one of the most robust additions to the game. Multipart diplomatic overtures can be made, and proposals can have multiple parts and quid pro quo exchanges. You can choose a "tone" to set with your approaches, and everything you do in the diplomatic arena affects the other nations' regard for your own.
The only problem with the diplomacy aspect is that you receive far less feedback on your overtures than you put in. Complex proposals are met with simple responses like "Your proposal has been rejected," without any indication of why or what it means for future relations with that power. Diplomatic systems in games like Sid Meier's Alpha Centauri, while nominally less flexible, give you a better sense of interacting with other nations and thus feel more like actual diplomacy.
The victory conditions have also been adjusted. Instead of just the three all-conquering objectives of the original, Call to Power II allows for a peaceful victory, in which a nation achieves a permanent alliance with every other nation in the game. The alien-cloning victory of the original Call to Power has been replaced by a science victory, in which your goal is to build the Gaia Controller and all of its components. This is much like the Alpha Centauri victory of the very first Civilization game.