Introduction: Andrew Lucard has written an excellent review of Cthulhu by Gaslight, 3rd edition, so I'll be taking a look at the PDF itself, which has been corrected since his review. The PDF was viewed on a PC with Acrobat X, and iPad 2 on Adobe Reader and other readers.
The PDF viewed is CHA23123book_rev.pdf, dated 4/5/12. On the PC with Adobe Acrobat X, I was able to view the document. I had problems viewing the document on an iPad 2, until I upgraded my Adobe Acrobat to the 4/10/12 version. iPad 2 apps that had problems viewing the document were previous versions of Acrobat, iBooks, PerfectReader, pdf-notes, PDFReaderLite, and Epson iPrint. The viewing problem is that the background on the boxed text is too dark to read the text.
Format: The PDF comes in a 196 page book, divided into Victorian Characters (player material), The Victorian World (player and Keeper historical source material), Strange Britain (player and Keeper occult and mythos source material, NPC stats, and adventure seeds), Gaslight Adventures: The Night of the Jackals (introductory adventure) and The Burnt Man, Appendix I: Suggested Sources, Maps and Handouts for the adventures, and Character Sheet. The PDF is in black and white, in a double-column format.
Price: The price of the PDF is $20 versus the MSRP of $28. That's only an $8 difference, and some online sellers may have the print version at lower than MSRP. If you must have a print version, you might as well buy it printed. However, the PDF version has some advantages over print, particularly for the player material.
Victorian Characters: The player material consists of the Victorian Character generation section and The Victorian World historical source material. A major advantage PDFs have over printed copies is that the Keeper can print several copies of player materials, so each player can have his own copy. The Victorian Characters section is about 20-some pages printed.
Victorian World: Based on historical England, the Victorian World source material can be used by both players and the Keeper. An advantage of the PDF format is that Keepers can easily share this information with the players. Avid players may read ahead of time this section before the game. Or a Keeper can print out the pages and cut out relevant information (eg. Underworld Slang or English law) as handouts to players during the game. This section is about 45 pages long.
Strange Britain: This section consist of Occult in the 1890s, A Gazetteer of Selected Strange Sites in Britain, The Cthulhu Mythos in Britain, Victorian Fictional Characters, A Compendium of Victorian Non-Player Characters, and Victorian Scenario Suggestions. Like the Victorian World, the Keeper can provide the occult information to players as printed handouts ahead of time or during the game, depending on their occult skill. The Gazetteer and Cthulhu Mythos are prevented something like one-paragraph adventure seeds. A crafty Keeper can definitely print this information as handouts for unfounded rumors and red herrings for gullible investigators. The remaining sections are Keeper material to add unique NPCs, stock NPC stats, and suggestions on running Victorian adventures.
Gaslight Adventures: Cthulhu by Gaslight includes two adventures, The Night of the Jackals, and The Burnt Man. The Night of the Jackals is an introductory adventure, still challenging for experienced players. Both come with handouts to print and provide the players. Both also include atmospheric art that can also be used as handouts to show players what their investigators see.
Suggested Sources for Victorian Roleplayers: This section lists further reading of and viewing Victorian fiction, Cthulhu Mythos fiction in Britain, and Victorian Roleplaying.
Maps and Handouts: Cthulhu by Gaslight provides maps and handouts for players for the game adventures, plus a map of London. A larger map is printed in black and white, with additional blue for railway and underground.
Character Sheet: The first page of the character sheet has the Call of Cthulhu stats, while the second page is for personal data and other background information. Unfortunately, I was not able to fill in the sheet in Acrobat.
Conclusion: The PDF format allows the Keeper great flexibility in providing Cthulhu by Gaslight to players. iPad 2 viewers should upgrade to Adobe Acrobat, version released on 4/10/12.
[5 of 5 Stars!]