This is a very impressive product. The PDF options, which is what I bought for now, are great for documenting your world in the appropriate level of detail. I prefer the loose pages the most. They allow me to complete them, collect them into a single pdf (player and DM editions) and potentially upload the master PDF to Lulu to print a copy for each of my players.
The physical book is very impressive. If you are on the fence, invest $5 and get the PDF set, then decide if the print book is for you.
Fat Goblin consistently publishes material that make your games more fun, enriched, and with products like this, more ogranized.