I share many of the reservations others have expressed about this novel. I particularly dislike the “little boy language” Carroll seems to find necessary for Bruno.
It is worth pointing out that there is an opinion that
Sylvie and Bruno is an astonishing masterpiece far ahead of its time. While clearly one doesn’t have to accept this position it is worth reading an apologia for the book. Here is one such:
http://popculturephilosopher.com/sylvie-and-bruno/