It seems most people here have never used (and not tried) racket.
I decided to use racket for my little sides projects, as
replacement for scala and clojure.
I choose it because it was clear for me i can't stand limitations
other language impose to me in way of style and boilerplate, the
racket macro (aka syntax transformer) system is the most advanced
i know to reduce the boilerplate to a minimum and so just write
what i want to express. In facts i rarely write macro because
writing a good macro demand you take care of errors syntax, i am
lazy in the bad meaning of the term.
I choose it because it's dynamic typed and i get more convinced
that type go on your way most of the time (expect complex
algorithms)(i write little projects, so refactoring argument is
out). It enable me to write code and eval it on the fly with
geiser (using enter! on the back), after eval the new function i
test it in the repl, hack until the function meet the requirement
copy paste from repl and boom i get a unit test. Because it as
eval and it will become handy one time in your programmer life
for sure.
I choose it because of it's sexpr syntax, as a heavy user of
emacs i know that other syntax is a pity.
Also because it has (and i use):
1. llar parser (implemented through a macro).
2. A pattern matching nothing to envy scala or clojure deconstructs.
3. An optional type system.
4. A contract system.
What i find hard as a new comer (to racket, not as a programmer
already now scala, clojure, half of c++ :), php) is
1. The broadness of the features the language offer, which
feature to use e.g.: class or generics.
2. The documentation is rich but lack of examples for the common
cases, so you need to read the doc of the function (sometime it's
huge).
3. Understanding how racket module works is quite hard and you
have the documentation, if you don't plan to play with the macro
expander (the stuff that run your macro) and some dynamic
features you don't really need to.
4. You need to 'register' the errortrace library if you want a
stacktrace, quite a surprising behaviours for me.
My opinionated conclusion:
Racket is the best language design i ever see, it's hard to learn
but make you feel learning an other language will just become to
learn a new sub-optimal syntax. Sadly the ecosystem is lacking
libraries and peoples and i am not helping in this way.