The chapterless book I read most recently was
Gilead, by Marilynne Robinson. It's an absolutely beautiful book -- stunning prose, heartbreaking story -- and it won the Pulitzer Prize. It's one unbroken narrative: an aging preacher's letter to his young child.
However, it certainly wasn't an easy read. Every time I stopped and started reading, it took a while to find my place and readjust myself to the narrative. I found myself rereading much of what I'd already read, and it probably took me over a month to finish (though I was reading some other books at the time). I'm glad I read it, but it'll probably be a while before I tackle another chapterless book. I think the writer
generally needs to throw a couple readability bones to the reader (and I say this as someone who always enjoys a literary challenge). Even
Ulysses has clear chapter breaks.
"SPEAK" by Laurie Halse Anderson is a good example of a great book with no chapters.
One of my favorite books!
However, it
does have clear breaks in the narrative, marked by the school quarters and the main character's report cards. Though they're not marked and numbered as chapters, they're still divisions in the narrative that function the way chapters do.