In addition to giving the DM loads of hooks for creating adventures (as already suggested) also definately include a chapter on "Stuff a PC should know" that quickly brings new players up to date on the most important things that anyone living in your world should know.
Most people I know at least prefer to just jump into a world, and that means a combination of "here's how the world is different from others" and "here's a bunch of great ideas that are specific to this world" are a great way to get a feel for a world.
Also, in addition to describing key features and the most important buildings, also provide tips and information on how to quickly grind together something typical for that world (rather than something extraordinary)
For eaxmple; information on how to quickly determine the key structures in villages in different regions, tips on regional cultural behaviour, a quick breakdown of who worships what in which location, the kind of dungeons and other quests most commonly available in an area, perhaps a list of sayings and lore.
One of the things I most often miss when reading a new setting book is how, when the PCs come across Meaningless Hamlet #2 I can quickly make something that´s unique and tailored to that specific setting rather than something generic.
Likewise as a player, one of the hardest things is to come up with something that really makes your character a part of this world, and some helpful advice in that area would really help the immersion, I think.