This was my experience, too. A Skeleton Key To Finnegan's Wake by Joseph Campbell helped me understand the overall themes of the book, and hearing Joyce read it helped me appreciate the language and the rhythm of the words. I found it more approachable once I saw it as a story told in wild poetic dream sequence imagery.
Listening to Joyce read it aloud: https://m.youtube.com/watch?v=M8kFqiv8Vww&pp=ygUcam95Y2UgcmV....
I had so much trouble trying to read him before understanding the intended pacing. It's more poetry than prose.