Hi there,
I’ve been working with multiple animation solutions through the years. I really do believe pencil is on the right path to becoming a good open source software for animatics, line testing and maybe somehow basic cleaning work.
The actual major issue I see, in order to be able to animate, is that it isn’t possible to move key-frames (or drawings) around in the time line. The current beta version only enables you to create direct animation, which is an animation technique you barely see in current films, unless in stop-motion.
A second less important issue I see is that the camera’s frame doesn’t show up on the drawing’s view. It is currently possible to pass through by creating a drawing layer that shows the frame. My comment here is that it is important to know while you draw where the frame stands so that your character don’t get cropped, or is way too big or way to small in the final render. This being said, I believe it would also be important that in the camera view, the frame stays proportioned to the drawings/content involved behind it. Situation: I want to create a 1080p sequence. My screen is to small to show up the whole frame. However, I need to see what my animation’s composition looks like. Right now, zooming out or in only affects the drawing. The frame stays wide, so I have no clue on my composition.
I hope this helps you target major issues that need to be fixed. Or someone let me know if you have solutions on these problems. I’m looking forward animating in this great software!
M. 
