The book: The Shadow Players Guide is an invaluable addition to any Wraith game. CH1 is a general introduction to playing Shadows and what they're after. CH2 is the Systems and Dirty Tricks chapter that not only includes new Shadow archetypes but also a host of new (and very vicious) thorns, tips on Harrowings and a top 10 of techniques for Shadowguides to use which is incredibly useful and is worth the cost of the book by itself. CH3 is an curious chapter that covers how Shadows behave in the other Dark Kingdoms - not exactly useful for every game, but an interesting read. CH4 covers Spectres and the Risen, CH5 covers the Eidolon, and CH6 is the standard series of essays on roleplaying. It's a very useful book, and I'd say it's pretty much essential for Wraith.
The PDF: Unfortunately, this was one of those books that WW decided to do as white text on black paper. While this was fair enough when it was in a printed hardcopy book, it's lethal when it's a PDF. I'd agree with the previous reviewer that a printer-friendly copy of this (and IIRC the Dark Reflections book, which was also white text on black background) would be vastly preferable here (unfortunately the security settings of the eBook prevent the reader from opening it in photoshop and inverting the pages and tweaking the contrast).
An even bigger killer is that the quality of the Ebook scan itself (at the time of writing at least) does not appear to be all that great - I can't tell what the resolution is, but I'd be very surprised if it was 300 dpi. This means that the writing is actually a bit hard to read even on screen - it's just about readable at 100% view but it's a bit fuzzy. It looks like the image compression settings are way too high - the compression blocks around the edges of the text are rather large and make it almost unreadable when viewed at 300% resolution.
So we have a double whammy here - the universal black background will kill the printer if you try to print it as is, and the text is a little difficult to read on the screen. Which is a great pity as this is a really essential book for Wraith. I can only hope that it is replaced with a higher quality, more printer-friendly scan.
So I'll give it 2/5 - I'd give it 5/5 for the material in the book, but the poor quality of the scan and the printer-unfriendliness drag down the mark. I can only hope that this can be changed at a later date.