In comparison, I think 4e is pretty damn coherent. Both in terms of the design, and in the DMing advice given. (I'm ignoring the intro "This is how you play" stuff... it's extremely superficial and the in-depth DMing advice later in the book doesn't match it, so I figure we can safely ignore it.) That's just my opinion from reading the books.
For example, there's bits in the DMG about the PCs looking to gather info in the local wizard's guild library, the DM hasn't yet established that one exists, but since it's plausible and the players have an idea he wants to run with, voila, yes, there is a wizard's guild. Or the quest section where players are encouraged to come up with quests and the DM assigns suitable difficulty and reward. That's pretty neat stuff and it goes far beyond the kinda-railroady introduction text.