Here's something that's normally not too fun to deal with in Python and Ruby: asynchronous operations. Perl 6 has promises, C#-style async/await, Go-style channels, and Reactive Extensions-style Supplies built in as first-class ways to deal with asynchrony, concurrency, and parallelism. It can also take advantage of as many threads as you'll give it. Since I deal with web services a lot, this is a huge boon for me.
But I don't really want to give a laundry list of features, because that alone is not a compelling enough reason to pick a language (P6 obviously needs to develop an ecosystem). As someone who appreciates both OO and FP, both static and dynamic typing, P6 really hits a sweet spot. I encourage you to look at Perl 6 as a new language with the feel of Perl but which solves many modern problems.
I actually like Clojure quite a bit and used Racket (with How to Design Programs) when I first began my foray into becoming a programmer. Here are a few reasons why I'm more excited about Perl 6 now than I am about Clojure (although I still think Clojure is great):
1) Async. While I was initially enamored of core.async, I've found promise combinators and supplies to be a more useful and higher level abstraction for the type of work I do. I also had huge problems debugging generated core.async code, but maybe that's changed over time. I suppose I could use RxJava with Clojure for supplies, but I have a feeling that it's not really seen as being in the same style. This is also why I'm not as big of a fan of Go as I once was, too.
2) As peatmoss mentioned, startup time. I work at a web hosting company and as you can imagine we write lots of small scripts. Clojure really can't compete in this area.
3) Gradual typing. Perl 6 supports gradual typing, with functions being checked at compile time and methods being checked at run time (the latter was a decision to allow both a powerful metaobject protocol and also easy interop with other languages using things like Inline::Python). I know that Clojure has core.typed, but that's not really what I'm looking for, although I do think it's an excellent project.
A final quality of life difference: Perl 6 has invested a lot of effort into awesome error messages, including things like suggesting a close lexical variable if you mistyped one. While every Clojurist learns to deal with the stack trace o' doom, there's something good to be said about this. :)
As a fan / dilettante of Clojure, I'd say no. The JVM is many nice things, some nasty things, but definitely not lightweight in terms of things like startup speed that I'd expect of Perl 6.
"The JVM is many nice things, some nasty things, but definitely not lightweight in terms of things like startup speed"
The jvm startup speed is actually surprisingly good these days. We were experimenting with writing several commandline tools with Scala, and didn't think they would work because of this "well-known" issue. Turns out it was fast enough even to enable letting Scala handle things like the code completion and still have it feel very snappy.
I'd agree that the JVM itself isn't so bad in terms of startup time. However, the last time I compared Clojure and Scala, Clojure took significantly longer to start up (even though what I was doing in Clojure was nothing compared to all the libraries I was pulling in with Scala!)
Edit: I should add that there's a Perl 6 JVM backend. While it's not as up-to-date as the default MoarVM, it could also be ready "for Christmas" :)
But I don't really want to give a laundry list of features, because that alone is not a compelling enough reason to pick a language (P6 obviously needs to develop an ecosystem). As someone who appreciates both OO and FP, both static and dynamic typing, P6 really hits a sweet spot. I encourage you to look at Perl 6 as a new language with the feel of Perl but which solves many modern problems.