Night's Dawn was so immensely frustrating. He revisits some of the same ideas in later books to much better effect IMO and skips over some of the terrible stuff.
Tap for spoiler
The biological starships were great but then we have the ghost of Al Capone possessing a body and leading a war against unpossessed humanity? That was fucking awful.
The Culture is nothing but gold though. Recently revisited Inversions and it's still amazing.