I came in to say Gravity’s Rainbow also. It felt like four different books and, yes, it was hard to focus with the tonal changes (iirc… it was a long time ago). Still found it worthwhile.

I have tried to read it three or four times and cannot get past the part about the banana tree and all the banana based food he cooks up. Not a banana hater but for some reason that part makes me kind of queasy and I put the book down every time