I learned that using code as data is more powerful than anyone who hasn't used Lisp can understand. Unfortunately, most languages make it a pain in the ass.

I long for macros almost every time I program something in Python.

I learned that having a powerful cross-platform standard library was more invaluable than I previously thought. :-)

I learned I lean toward being a purist.

I learned that uniformity in good (by uniformity I mean the everything is a list feature).

I also learned that if you are mildly obsessive compulsive, (counting) the brackets will drive you crazy, and you will just give up.

Which led me to learn that if a language achieve type uniformity without syntax uniformity, it will be awesome, it will have all the goodness of lisp but with more forgiving syntax

A local lisp implementation in my community saved an entire boatful of drowning puppies! Lisp is awesome!

I learned that coding in Lisp is almost as enjoyable as designing Architecture (the building kind).

i think Smalltalk was more of a mindfuck than Lisp.