Significantly better than the first book in this series, Whiskey and Water picks up the loose ends from Blood and Iron and sustains them through half the book, building to a much more satisfying climax consisting of multiple battles and tense magical standoffs. My gripe: why did I have to wait for book 2 for all that heavy worldbuilding to pay off?!
As with its predecessor, Whiskey and Water suffers from a surfeit of mythology and mythological characters, particularly when it comes to Devils. The complex, and apparently ineffable, rules of magic and Fae once again serve as the cornerstone for the major plots. This time around, I simply gave up trying to make sense of the magical guidelines and tried to enjoy the story. It worked. Sort of.
Several familiar characters return in this sequel, including Matthew Szczegielniak, Jane Andraste, Carel the Merlin, Morgan le Fey, Elaine (now Queen of the Daoine Sidhe), and the eponymous Kelpie, Whiskey. Joining them are some new faces: Kit Marlowe (the one and only); Devils Lucifer, Satan, and Christian (an unconvincing antagonist at best); archangel Michael; and several mortals who may or may not die over the course of the book. And again, it's difficult to tell who the "good guys" are.
Nominally, Matthew and his cohorts are supposed to be the protagonists. Jane Andraste serves as an antagonist, for her attempts to rebuild the Promethean Club may result in another war with Faerie. Meanwhile, Lucifer has his own agenda, as does the charming Christian, who poses as an apprentice to Jane. I found this aspect of the plot entirely unfulfiling. I never understood Christian's motivations--sheer malevolence, or was he working toward a greater plan?
There were few characters I could just sit back and enjoy. Donall Smith was one, because he seemed like a genuinely honest and good person. Like the other mortal characters, he suddenly becomes involved in an epic, centuries-old conflict. Unlike the other mortals, however, Donall actually has the guts to stand and fight. Aside from him, the best parts of Whiskey and Water happened around the climax of the book, when every petty conflict comes to a head simultaneously.
The rules that govern the Promethean Age seem too mutable. I'll again compare this series to the Dresden Files, by Jim Butcher. The Dresdenverse has a complex set of rules, but I seldom feel burdened or confused by them. However, that may be due to the excellent writing and characterization in the Dresden Files books. The Promethean Age series' complex ruleset may be its single worst feature, but it's the characters and conflicts upon which the success of these books rests. And for me at least, there's just too much magic, too many beings who are, at least from a human's very limited perspective, apparently omnipotent.
The preponderance of powerful beings presents a problem: when unstoppable force meets immovable object, something's got to give. When Dragon faces off against Prometheans, when Hell and Heaven duel, and when one Fae queen plots against the other, the battlefield quickly gets complicated, and the plot can become hard to follow. Unfortunately, Elizabeth Bear's problem is that she tries to do too much and is forced to try to balance too many characters and too many conflicts. As a result, while I enjoyed the book--particularly the ending--I'm still somewhat confused, and not entirely certain of exactly who won or even for whom I should have cheered. While I'm all for moral ambiguity, I like to at least have a hero.