I think PAIP is underrated (or maybe just unknown) because a) AIMA replaced it as the go-to AI text, b) there's no free online version (unlike SICP, PCL, OnLisp

I think PAIP is underrated (or maybe just unknown) because a) AIMA replaced it as the go-to AI text, b) there's no free online version (unlike SICP, PCL, OnLisp, etc), c) it's expensive. But it's probably my favorite of all the Lisp books I'm looking at now.