If it wasn't a big book, I'd say he's taking the piss.
[...] riverrun, past Eve and Adam's, from swerve of shore to bend of bay, brings us by a commodius vicus of recirculation back to Howth Castle and Environs.
Sir Tristram, violer d'amores, fr'over the short sea, had passen- core rearrived from North Armorica on this side the scraggy isthmus of Europe Minor to wielderfight his penisolate war: nor had topsawyer's rocks by the stream Oconee exaggerated themselse to Laurens County's gorgios while they went doublin their mumper all the time: nor avoice from afire bellowsed mishe mishe to tauftauf thuartpeatrick not yet, though venissoon after, had a kidscad buttended a bland old isaac: not yet, though all's fair in vanessy, were sosie sesthers wroth with twone nathandjoe. Rot a peck of pa's malt had Jhem or Shen brewed by arclight and rory end to the regginbrow was to be seen ringsome on the aquaface. The fall (bababadalgharaghtakamminarronnkonnbronntonner- ronntuonnthunntrovarrhounawnskawntoohoohoordenenthur- nuk!) of a once wallstrait oldparr is retaled early in bed and later on life down through all christian minstrelsy. The great fall of the offwall entailed at such short notice the pftjschute of Finnegan, erse solid man, that the humptyhillhead of humself prumptly sends an unquiring one well to the west in quest of his tumptytumtoes: and their upturnpikepointandplace is at the knock out in the park where oranges have been laid to rust upon the green since dev- linsfirst loved livvy.
From the book's wikipedia page:
Critics disagree on whether or not discernible characters exist in Finnegans Wake.
How can anybody take a book seriously, which is so unreadable that critics can't even agree upon whether it has any characters or not? Holy frig.
I suspect the book is so famous simply because it becomes an obsession for people to try to make sense from it. They can't let it go. And then they have to justify their interest by claiming it to be a significant literary work.