As Isaac Schlueter wrote this week in a post for the Node.js Google Group:

Streams are more consistent, faster, and 100% backwards compatible asof 0.10. The "compatibility mode" aka "old mode" is folded into theAPI more cleanly. You can pause() a flowing stream, and then startcalling read() again safely. We'll keep exposing streams from coreAPIs, and advocating extending the stream base classes in userlandprograms.

If you want to learn more about streams and stream3 in particular, watch Isaac’s talk from our “A Midsummer Night’s System” meetup.