Timed autosave: no more lost work
Spiro splines: an exciting new way to work with paths, fully supported in Pen, Pencil, and Node tools
Auto smooth nodes: a new type of node that keeps the path as smooth as possible as you move it or its neighbors
New modes in Tweak tool: pushing and jittering whole objects, scaling/rotating objects, deleting and duplicating using the "soft brush"
Reworked, much more usable snapping system and a Snapping toolbar
New path effects, including sketch, hatching, envelope deformation; effects can be stacked and assigned to groups
A huge collection of preset filters in the new Filters menu
New cairo-based PS and EPS export: improved quality, more features supported, fallback rasterization for filters and transparency
Spell checker for text objects in a document
Many new extensions: restacking, calendar, printing marks, cartesian and polar grids, interpolating attributes
Optimized SVG code options, now with their own Preferences page
Many other improvements, usability tweaks, memleak stops, and misc bugfixes