We have a good sized clojurescript SPA in production, and it has been a real joy to work with. We are using Reagent, which when coupled with FigWheel[0] goes a long way toward mitigating slow startup, as well as "tooling" issues in general. The live reloading is a fantastic experience.

Sourcemaps have been a big help for debugging in general, though we have had several instances of bugs taking a bit of effort to get to the bottom of because of some deep javascript stacktraces -- for the most part the java side of the compiler hasn't been a big deal. Many of these have been type related bugs, so we're looking into adding some schemas[1] going forward where it seems appropriate. Despite those issues, it has overall been a huge productivity boost. We've also witnessed this story only improving with time.

The community truly is fantastic. Lots of very smart, friendly folks doing interesting things.

[0] https://github.com/bhauman/lein-figwheel [1] https://github.com/Prismatic/schema