The learning curve is small if you have a math or cs education, if you've been exposed to another functional language or you naturally think in s-expressions.
If you are just a random python programmer and you looked at arc I could see it being challenging. The axioms of lambda calculus and functional programming are concise and simple but that doesn't mean the concepts they imply are also simple.
I agree The Little Schemer is a great book. Along with SICP, On Lisp, etc.
In the end it is worth the trouble to learn at least one lisp dialect. It'll improve your coding and make you question why you are writing imperative-language-001 all day long.
