The novel :
... takes as its premise Franklin Roosevelt's proposition that Alaska, rather than Israel, becomes the homeland for the Jews after the Second World Warwrites Alison Flood in the Guardian :
Some bloggers questioned a work of alternate history winning science fiction's most coveted prize, but Chabon told an interviewer in America that science fiction had "porous" boundaries, and that "there is definitely room in it for a work of alternate history".Incidentally, maybe you can judge a good book by its cover - I bought the novel in hardback because I couldn't let such a pretty edition pass me by. I look forward to reading it!
You can listen to an extract here and browse inside it here.