Main focus has been to expand from just the use-case of accepting a single JSON document, and unpacking arrays to NDJSONifying JSON streams in general. So a stream of objects will usually just be converted to NDJSON. Also because the default is to unpack an array we now have an option that says you don't want that which allows you to preserve arrays -preseve-array.
Aside from that small improvements, like a friendlier error message in some circumstances.
Full Changelog: v0.3.2...v0.4.0