PAIP is one of my favorite books ever, but taken as a book about the craft of programming, not about AI. AI has grown, and the broadness of AIMA matches the subject. (It does need another update, and I heard they're working on one.)
PAIP is also very, very high on my list as well. I'm very pro-lisp and still develop new projects in lisp (CL, Scheme) and promote it when/where I can. But the person who picks up PAIP wanting to learn AI might not necessarily want to worry about picking up lisp programming skills at the same time (nor is learning lisp strictly necessary). This is why AIMA is still the best option, IMO, because it employs a language agnostic approach.
