Features

Vector-based

Even when changing the target resolution of a project, the only pixelation will occur in imported raster images, not the line components.

Temporal resolution independent

Animation-keyframes are automatically interpolated by the computer, resulting in smooth motion

Pentablet-friendly tools

The draw tool already reads the pressure sensitivity channel off your favorite tablets, for natural line weighting, and more to come!

Artist-oriented design

While it may not be obvious in this early state, Synfig (and its proprietary predecessors) has been designed from the ground up with animation workflow in mind.

Built-in CVS support

I haven't tried this yet, but I saw it in the file menu and it looked nifty, so- Hey, feature!

Path-based Gradients

Unlike purely SVG-based vector software, and most consumer-level animation programs, Synfig has full support for gradient paths - gradients that follow along a drawn shape. This allows artists to easily add soft shading to animation without the trouble of painting it onto every frame.