Recs.
Updated
SpecsUpdate
Pros
Pro Easily embeddable
Racket is famously embedded in the game engine underlying Naughty Dog's Uncharted and The Last of Us games, because it proved to be so easy to embed.
Pro Racket was designed to teach functional programming from the start
Racket is based on Scheme (LISP Family) and is very similar to Clojure. So there are a ton of (). The reason it is easier to learn is that it is not trying to be "Pure" if there is even such a thing in terms of Functional Programming. The great thing about Racket is it has everything included. You get DrRacket for developing programs. You want to add a picture to your software you can insert pictures. If you want to add libraries just open the package manager. The Syntax is an opinion but it really does feel easier to see what is happening since everything is in brackets)
Racket is a really a Programming Language for making Programming Languages. So there are smaller syntax Racket called Student Racket which makes things easier to pick up.
Pro Subtly encourages functional programming
Racket makes it inconvenient to pursue imperative habits while encouraging functional programming by Lisps's syntax. For example, the syntax for defining a function is almost the exact same as defining a variable. In addition, Racket has a strong set of higher-order functions built in to the language.
Cons
Con Restricted macro system in the name of safety
While about half of the abilities of Common Lisp's macros can be had simply, the other half (many of those found in "On Lisp") are impossible or extremely difficult to replicate.
Con Embrace, Extend, Extinguish History
Racket has a long history of employing the Embrace, Extend, Extinguish strategy popularized by Microsoft in its relationship with other Scheme implementations.
Recommendations
Comments
Flagged Pros + Cons
Con Not standard Scheme though standard Scheme is supported
Going from Racket to standard Scheme can be a little confusing as you forget which things are racket specific.
Pro Free resources to learn
Includes several free online books and great documentation.
Out of Date Pros + Cons
Con Slow (see benchmarks vs SBCL)
http://benchmarksgame.alioth.debian.org/u64q/racket.html
Racket compiler and runtime trades safety(contracts) for a slight speed reduction