The guys over at Hooked Gamers let us know that they've already ripped out a review of Katauri's King's Bounty: Armored Princess, in which the give the expansion pack a score of 8.2/10. It doesn't sound like the reviewer has ever played the original title, though, as demonstrated by his conclusion:
King's Bounty: Armored Princess has a forgettable story and dated graphics that seem borrowed from much older medieval fantasy titles. However, its gameplay is superb. The turn-based combat is the main component of this game and fortunately its strongest draw. While easy to learn, it is deeply strategic and very satisfying, especially when defeating an army that is much stronger than your own.
The overall formula of island hopping also proves to be very addictive. Clearing an island of all of its monsters and loot provides a great sense of pride in your army. Traveling to the next island, and observing the new landscape and atmosphere, results in a sense of wonder. And finally, those feelings of pride and wonder are dashed when you realize the armies on the new island completely outclass your own. Of course, that's what makes the game so much fun.