The Necromancer WoHF box is a lot more detailed than the old 32pp booklets, but they do contain tons of hex-specific info, in very terse format. Certainly enough to riff off.
The Necromancer CSIO book expands the entries from the original a bit, but doesn't add a huge amount to play IME; either can be used* equally well (although I prefer the original Wraith Overlord, the version in Nec CSIO has some editing issues). "Sure, there were enough location entries to be surprising for a while. Then one started to go to the same locations again, and what kept it interesting was the combination of random factors with remembering (assisted by notes) what had happened there before, and applying consequences." - that fits my experiences precisely. The written material is a jumping off point for the DM, not the be-all and end-all. But it's definitely sufficiently complex that the GM can't predict what will happen. Eg I had no idea that my first session would turn into a farce with different PCs' routes fleeing through the back-alleys after a fight all leading them into the Bywater Bath-house.
*The original is superior in a few ways, such as site-specific rumours, and a few NPCs have been lost from the 3e version such as the original's listing of academic staff at the School of Ancient Knowledge.
