I have used its JSON features for real-world stuff and loved it.

I have stored procedures doing a bunch of stuff and returning a nicely formatted JSON object that makes the job of the application code a lot easier.

One thing I dislike is that the friction for initial development and prototyping is a little too high.

You have to have scripts lying around to re-create the functions when you change it during dev.

And logging/debugging/etc is harder and not as flexible.