It's just a straight up must read.
I'm sad he described PAIP this way. To me, PAIP isn't even so much about Lisp or AI as it is about how god damn awesome Peter Norvig is. I think my programming became much better after I studied his style.
Bottom line, PAIP makes you a better programmer even if you never intend to use Lisp for anything.
You should learn enough Lisp to read PAIP, in other words.
Common Lisp: A Gentle Introduction to Symbolic Computation:
I used Eclipse and CUSP, it's alright. It could really help you get started. But I wish I had learned Emacs earlier. The only thing I will continue to use Eclipse for is Java programming (which thankfully I don't do much of these days).
Because emacs is the more powerful long term option, I will continue to make it my primary recommendation. I'll recommend Cusp/Eclipse to those that just don't care about emacs (now or later)
I think they made enough good points that my new policy will be to recommend Emacs, but mention Cusp as an alternative.