The characters are well developed, and the author's research and experience with autism rings true. But, most of all, one of the major characters is evil personified. You trust Max's instinct, and it comes through very early in the story.
But it is Budo who soars, and earns our tears. He sees his fellow imaginary friends disappear day-after-day (Budo has existed much longer, as Max needs him more), and his own nonexistance is his major fear.
The greatest praise that I can heap upon this book is that I loved it. Read it, learn from it, and pass it on.
It is that important.
'Memoirs of an Imaginary Friend' will published in August 2012, by St. Martin's Press.