Basically doubling the complexity of an app. If you need a fair amount of front end interaction, fair enough, but many apps would be a lot simpler with Django templates and a bit of jQuery.
Both my personal blog and business run on it in production. See my profile for links.
The biggest issue was deploying it since you need python and node. Still a work in progress, and docs are severely lacking.
But I did add a single-click deploy to Heroku:
https://dashboard.heroku.com/new?template=https://github.com...