Literary awards often go to novels that are interesting but not perfect; veteran Irish novelist John Banville's latest, the surprise winner of this year's Booker Prize, is an exception: It's ''perfect,'' but not especially interesting. In a time-split chronicle of loss, a stiff, emotionally constricted widower deals with both the recent death of his wife and a boyhood episode, 50 years past, involving the alluring children of a family that spent a summer in his town. It's less a great novel than a fine, showy soloist's chamber performance a lesson in the usefulness of an unreliable narrator when one wants to withhold crucial information, a demonstration of how precise, almost fussy language can reveal character, and a reaffirmation that, even after countless incarnations, sinister twin children never lose their goose-bump value. Banville's craftsmanship and exactitude are always in evidence. But, for a novel that unfurls a virtual thesaurus of adjectives to describe the ocean and sky, The Sea is, ironically, a bit too dry and airless for its own good.