The 3.4 release series brings around 90 new features to RRF compared to release 3.3. Major new features include input shaping, thumbnail image display in Duet Web Control and on PanelDue, more control over how to react to unexpected events such filament errors and driver warnings, and heater power feedforward for tighter temperature control of high-flow-rate hot ends.
Important: please read at least the Upgrade Notes section of the release notes before upgrading!
Consolidated release notes (for those upgrading from RRF 3.3): https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x-RC#reprapfirmware-340rc1
Incremental release notes (for those upgrading from RRF 3.4.0beta7): https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x-Beta#reprapfirmware-340-post-beta7
User of Duet with attached Single Board Computer, please upgrade via the package server. Users of Duet in standalone mode, use the files here. Preliminary builds of PanelDueFirmware with thumbnail image support are available at https://github.com/Duet3D/PanelDueFirmware/releases/tag/3.4.1-pre1.