There are more recent videos: https://www.youtube.com/watch?v=ecVv2IB7f5k

Here is "Hero" made with Blender, for comparison: https://www.youtube.com/watch?v=pKmSdY56VtY

Blender's pseudo-3D has more freedom with camera moves, but the capabilities look pretty similar otherwise.

Both clips are impressive.

I guess the question is: how powerful/useful are the tweening and "bones" features of synfig?

I see what look like obvious examples of those features in the demo.

The Genndy Tartakovsky style of the other demo kind of obscures whether those features are similar in blender.

That same clip has been going around for nearly a decade. Shame there’s little more to show for the software; I think that’s telling in its own right.

It hasn’t been mentioned in this thread yet, but OpenToonz seems like another fantastic piece of FLOSS software for 2D animation. If it’s good enough for Studio Ghibli and Matt Groening (Futurama), then I dare say it’s good enough for a great many other animators.