I only made it past the first 4 books. Does it later devolve into overt Objectivism?
You make it that far? One book was enough (and by "enough" I mean "about 500 pages too much, and if I'd known what a waste it was, I'd never have read the whole thing") for me.
"Wizard's First Rule" should have been called "If you were paying attention in the first 50 pages, you can just go ahead and skip to the end, because everything in the middle is just artifice to set up a surprise that's not, in any practical sense, surprising."