It's definitely not the hardest "arthouse" novel (or whatever you call it), I found Gravity's Rainbow by Pynchon so much more harder, and Beckett's Three Novels (i.e. Molloy, Malone Dies, The Unnamable) was likely the most difficult text I attempted to read in my life. Even then, I think it's still pretty difficult for an average Western reader in 2020s, our literacy attention span and interest is very low. People should definitely attempt it though!