Congrats on the release. I'm excited to finish reading the book. I just thought you should know, however, that there's a minor mistake (I think) in some of the walkthrough stuff in the pdf. On page 56:

  >  (defun pudding-eater (person)
      (cond ((eq person 'henry) (setf *arch-enemy* 'stupid-lisp-alien) '(curse you lisp alien – you ate my pudding))
  	    ((eq person 'johnny) (setf *arch-enemy* 'useless-old-johnny) '(i hope you choked on my pudding johnny))
  	    (t '(why you eat my pudding stranger ?))))

  > (pudding-eater 'johnny)
  (I HOPE YOU CHOKED ON MY PUDDING JOHNNY)

  > *arch-enemy*
  JOHNNY

arch-enemy at this time should hold the value 'useless-old-johnny, not 'johnny