Yes, the Java stack traces are probably the worst "ugly" thing in Clojure but from my experience the simplicity of syntax (not to be confused with familiarity, familiar != simple) makes it much easier for someone who's never programmed before to start writing Clojure code vs many other languages where there's a lot of syntax to that you simply need to "know" to get going.

Also, on a more advanced note, I've used https://github.com/ptaoussanis/timbre with great success to get nicely formatted and colored Clojure errors and stack traces.