What I notice most about Dennis Lee's yesno is the pervasiveness of the verb to be in certain sections of the book.
...

fumbumbling what
aleph? whose googoo? which syllab? Test-living which
schizoparse of am? (p. 27)

....

Deep
is, and be
struck. Be stricken.
Be amnioflex of the daily, as
things wriggle free of their names,
subsist in
sheer diggity fiat. (p. 44)

...

You fold you are
folded, late-breaking primate, and
brought to who-new.
Fold you are
null again, nil again, knell again - one-swat no-
see-um & whose. You
fold you are un:
stud of no
throne no dominion, kingshit of doodly.
Frag in the mean of let-be. (p. 41)

-- Dennis Lee, yesno

I can't help thinking of editing manuals and writing workshops that preach the elimination as often as possible of all forms of be. Is is the weakest verb, is'll drag your writing down. Generally true, but Dennis Lee transcends generalities. He's not dealing with grammar's weak links, he's posing existential questions. What is after whatever apocalyptic ending may be coming? Nothing is. No-one is. What is the language to write about being and the frightening fallout of future not being? What is language after all?

And why on earth didn't this book win the Governor General's award?!