Another Gaiman fan here, though I've only read a few of his. I really liked American Gods and the sequel Anansi Boys, and I don't know if I've ever laughed out loud at any book more than his collaboration with Pratchett, Good Omens.

Re being mediaeval, I call BS. It's fantasy. That means he can write gender roles and power relationships however he wants. I haven't read any Martin, but I've read way too much fantasy with drawn-out rape scenes obviously intended to titillate, even when the female characters eventually get their revenge.

On Paradise Lost ... Yeah. But I feel like Pullman's work deserves to be fully appreciated, and that means being familiar with his inspiration. All I remember from reading Milton in college is dreaming in iambic pentameter.