I finished Let Over Lambda recently. I'm not an experienced lisp programmer but it's strangely readable if you allow yourself to not understand every little detail of the Common Lisp code. For example I hadn't read On Lisp. I had read The Little Schemer.

It's a wonderful tour of advanced macro concepts. With several of the macros presented I found myself saying "well that's just x language feature in y" but that's missing the point. The point is that Common Lisp allows you to implement your own language features, with macros of course!

This chapter is a wonderful climax to the whole book. Lisp moving Forth moving Lisp reminded me of the intertwined nature of DNA, RNA and proteins in Biology.

There's great humour throughout the book, I especially enjoyed the little sideways jabs at Scheme programmers!