I was a flash user. And I was finding an open source alternative and Synfig is the closest thing to it. My first impression is that it is very different from flash. It is not anything that I was used to. It lack the good brush tool that flash has. I was a bit confused thinking that I may not be able to do much with it.
However, after reading the manuals and using it for a while. I find that it can do anything that I want to do in animation and more. The blender and tweening is much better than flash. Although I have to say flash is a bit more initiative. flash can do frame by frame animation easier with its onion skin and stuff.
I was still learning though. I hope more people could know this software.