What he said (more or less)
Of the 2 books (there are 7* actually) one of them is pure fluff. Not a single rule in it (The World Guide).
You can read more about the setting here
Notice that one of the biggest complains the fan base has is that 3.x do not do justice to the setting.
It is a dounting taks indeed. But I been playing BRP since 1999. I love the system (mostly playing CoC, Delta Green and the ocasional Stormbringer game) and I enjoy, a lot, the IK setting.
Now with the Generic BRP I'll have the chance to convert the setting I love in a system I love.
Awesome, eh?
*7 books not counting the original adventure trilogy (now in a single volume) and charcter primer (now the 2 huge books mentioned above)