Not much in the way of previews is yet available - the cover is up at the link for you to appreciate - but I am certain that The Book of Tyrael will be choc full of beautiful artwork. With supplementary materials like this, Blizzard always delivers. It's the main reason I keep buying the expansion collector's editions: I want those books!
The Book of Tyrael will certainly be a fine collector's item for fans of the Diablo franchise. Are any of you readers Diablo lore junkies? If so, this should certainly answer many of your questions (and probably raise a few more, as well)!
Editor's Note: Corrected the original date.