I remember learning about lisp, and how to use the primitives to write the rest of lisp 1.5 in those primitives in my matters programming languages class ( thanks Tom Murtaugh). I always found lisp interesting, but at the lisp 1.5 level, it isn't all that easy to use. Fast forward to common lisp or clojure, and usability increases, but there is still a big learning curve as it isn't like other languages. In essence, you are writing the ast directly rather than having a compiler move from a vaguely English form to the ast. In the end, the syntax is a plus because it makes macros a lot easier.
One note, I believe oop is in similar 67, which came before Smalltalk.