I've never read it. Although as an UG I read Ulysses, and even then I felt that a degree in theology is essential just to begin to understand it. Although religion is only part of it all. Joyce wrote deliberately for people to study his works for ever and ever, amen.

But FW was a favourite of Robert Anton Wilson, who studied it for decades, and he believed it to be, IIRC, the greatest ever work of literature. And Wilson was smart, if a little eccentric. He's worth listening to on FW, if you can find the recordings of his speeches.