Just wanted to share my initial first impressions of Synfig. And since the focus of this post is on features it seemed appropriate to post this here. The most overwhelming thing is when you first start Synfig and are confronted with an onslaught of floating windows. Synfig should take a page from Blender’s book and make it a goal to have a unified non-overlapping interface. Of course having the ability to “un-dock” portions of the UI and have them display on another monitor is useful. And that GIMP (GTK) look is and always has been visually ugly. The interface should show the tools and information the user needs, but be in the background. It would be nice to see QT implemented for the UI or at least take the current design and slim it down.
Everything as a new “layer” is a bit overwhelming and having to encapsulate the data to make things more visually workable is more of a hack word around I think. (Of course it works in the short term) The layers of transforms (ie. effects, translations, scales, etc.) should be applied to the selected/active object and give the user control to apply outside the object if the effect/transform requires.
I’m curious why points are referred to as ducks. It seems documentation wise it would be easier to talk across applications if they were called what the common term is…unless there is a reason they are called ducks? And a big error keeps occuring on the wiki. Sometimes I get a repeated error messages and the impression that the docs won’t load. That is a bit disconcerting I’m sure to new users.
Currently, I’m running on Windows to use Synfig. And now that I’m not running off of my phone for internet I’ll give compiling on OSX a try. But I’d recommend not even posting up an install (even with a warning) until it for sure works. That will lead to many trying it, seeing that it doesn’t work and walking away.
I am amazed by all of the effects that are possible in Synfig. I think thats definitely a strong point of the application and I look forward to exploring them all in detail.
Features I miss from Toonboom and ASP (some perhaps that a Synfig user can direct me to workarounds 
):
Bones. It’s discouraging to see that bone development was talked about back in 2008-2009 and it’s 2011. This feature would greatly amplify Synfig’s use. Of course I understand that developers are limited and you don’t want to implement a halfway developed feature.
Switch layers. It may not be necessary at all in Synfig to have anything like that. I get the impression that waypoints can function in that regard, but I may be misinterpreting things.
Rotating light tablet/canvas effect. It’s really great when drawing to be able to rotate the canvas and it’s something I miss in Synfig.
I’ll post more here as I go, but those are my initial thoughts.
Brushes. I’d love to see mypaint brushes or Krita’s brush system implemented into Synfig for frame by frame based animation. Would be incredible even to be able to paint a character and animate the image elements with the bones discussed earlier.
Audio support of some sort. Just for basic lipsyncing would be useful.
Disclaimer: I did use Synfig early in it’s development. So I am sort of familiar with the app.