So if you use any ClojureScript libraries in production, expect to run into strange issues and submit bug reports that are not responded to for months on end. Nothing against their authors, it's just the nature of writing niche tools.
All that said, once devs are up to speed, and designers have a modicum of tooling, it's the best system I've used so far.
Personally, I ran into an issue with the Chas Emerick's testing framework and lost about a day of dev time trying to track down the issue. I never did figure out what was wrong and ended up just scrapping and starting over. In the end, it would have been nice to have some alternatives, but there really weren't any mature ones at the time.
Contrasting the situation with a language like Python where, should I run into an issue with Py.Test, I can always switch to Nose or numerous other frameworks.
Searching for documentation for CLJS is also a bit rough. I ended up relying on ClojureDocs for the most part, but because CLJS transpiles to JS and not JVM code, there are some undocumented idiosyncrasies. This also complicates troubleshooting because the errors are thrown by something like line 6400 of the transpiled code, not line 20 of the code you have been writing.
I still love the language. I am even taking part in a CLJ/CLJS specific hackathon next weekend. However, I have trouble recommending it to others without caveats. Most of which are due to the language's relative immaturity.
Once you have these working, errors are linked to line 20 of hte code you are writing.