Grease Pencil 3.0 was going to be included in the LTS release which preceded 4.3, but various complications prevented it from being ready for the main branch. Needless to say, it is finally HERE. In spite of the changes, there's a lot that is still familiar, and you won't need to re-learn a great deal in order to use it.
Brushes
One big change is how brushes are stored, accessed and shared. They are now part of the asset system.
Because they are saved as assets, they can now be accessed in new .blend files.
Tools, Menus, where to find things
The Draw toolbox has been re-organized, grouping together tools into handy pop-outs.
Tint is now a brush; Cutter has been renamed "trim".
The edit menu has replaced the Transform Fill tool with a new Gradient tool.
Where Transform could be toggled between Move, Rotate and Scale, the Gradient tool now works on all three by clicking and dragging. It works on both gradient and texture materials.
Some modes such as Curve editing have been rethought. Curve editing used to be accessed in Edit Mode next to the select buttons. This would change your edit points to bezier curves with handles, and you could edit your strokes like you would a curve object.
You can now change your points to a variety of curve options for editing. This is now found under the Stroke Menu when in Edit Mode
Layers, Stroke settings and Modifier menu
Layers still function the same, but with some added settings which make workflow SOOOO much better!
Layer groups are now a thing! You can now group layers for easy organization. Additional tools such as Merge Group have also been added.
Stroke Settings were found under layer properties, allowing you to modify some stroke settings such as thickness scale or curve resolution.
Stroke Thickness was where you could set how the width of a stroke would be seen - either World or Screen Space. World would lock the stroke thickness to the scene scale, whereas Screen Space locked the thickness in relation to your viewport. This caused a strange scaling issue if you zoomed in or out.
This has now been removed, and the stroke thickness can now be set in your brush settings and can be measured in world units or pixels.
Also the scaling will be locked to your scene and not in relation to your screen.
The Modifier pop-out menus have been brought in line with the rest of Blender.
You'll notice here that Geometry Nodes can be added as a modifier for Grease Pencil Objects too!
Geometry Nodes
Geometry nodes can now expand what you can do with grease pencil - and probably warrants its own article.
Backwards/Forward compatibility:
Great care has been taken in converting older files into the new architecture. This is such a credit to the developers. Everything you created is there - palettes, materials, layers. There may be minor issues with a couple of modifiers such as noise, and any brushes you created in earlier versions won't be imported, unfortunately.
Opening newly created files in an older version will not work, since the Grease Pencil architecture is heavily rewritten. So do back up those legacy files saved in the original version!
Conclusion:
Aside from these changes, Grease Pencil still seems to function much like before, so workflows you might be used to are just made faster and more intuitive. If you'd like to see these changes in more depth, check out my video covering all of these key areas here!
https://youtu.be/zrIPbky8Xf8
