I loved this book as a kid, but I'm really not sure I would recommend it today. The Lisp of that era had "dynamic scope," and a great deal of Allen's book is concerned with fancy data structures and techniques to implement it in a reasonable fashion. But today I think we understand that stuff as basically wrong, and that "lexical scope" works better (and is much closer to the original lambda calculus that served as an inspiration). There are probably some proponents of dynamic scoping, but I think it's a lost battle.

So definitely yes, if you want to implement a historic Lisp. Otherwise, not so much.