Try the book reviews thread.
I have it and it is a small approx. 6" x 4" hardish back book.
It is a series of Sigmar's adventures, with some interspersed line drawings.
Very Sigmar only orientated.
It's an ok set of tales but it is obviously set whilst he was alive and so gives info on the various tribes pre-unification.
If you want something with more Empire background, there are reviews on "Sigmar's Heirs" in the Library.