The Sony SmartWatch 3 is now receiving the Marshmallow update, aka Android Wear 1.4. In about a week, all SW3 users should have gotten the new update, which pushes Google that much closer to updating all Android Wear smartwatches to the new version (isn't it nice when OS updates are centralized like that?).
The 1.4 update brings support for calls using a loudspeaker (for those watches that have one), dictating messages for chat apps (Hangouts, WhatsApp, Viber, WeChat and a few more) and additional gesture support.
PS: The update will arrive over the air, but if you need it now, you can download it from here.