Compared to most Tim Powers book, this is neither terribly exciting, and even a bit of a drag at times. Compared to most historical fantasies it's a clever, entertaining, swashbuckling romp as Brian Duffy, irascible Irish mercenary, is finagled from Venice to Vienna, hired to be a bouncer at an inn famous for its beer. Crossing the Alps on the way to gainful, if unlikely employment, he is attacked and waylaid but also protected by a cavalcade of mythical monstrosities, indicating that there is a lot more going on than meets the eye. Indeed, noting is as it seems, not even Duffy himself, who must protect a rare and magical brew of dark beer from the invading Muslim horde abut to lay siege to Vienna.
It's fun, but the writing drags here and there, and some of the plots are undercooked and the mingling of myth and history, Power's trademark intellectual trick, isn't quite as thoroughly developed as you find in later works. Read this if it's your first Powers, or if you;re a bit of a completist.