The 7th edition books and PDFs of Call of Cthulhu have fantastic art and offer updates to the previous rules. The Investigator's Handbook is a great resource for makign characters and giving players background for the standard campaign timeline. If your looking to just play this is the book for you. If your looking for more in depth Call of Cthulhu rules knowledge or looking to run a game, go with the Keeper's Rulebook.
The PDF seems to load slower than most PDF game books I have. I think it is either the hight quality art or maybe the PDF is not optimized. Great purchase and worth the value though.
[5 of 5 Stars!]