I think it would be a good idea to have all major issues/bugs/flaws listed in one thread so we can help solve them.
For example - I have noticed a weird bug when animation is put within a symbol: it looks ok in Chrome, but in Mozilla it's not displayed properly, it has some strange 'jumps' in animation. Also, in IE9 the gradents aren't supported, but I was notified about that in Edge, with alert below the stage.
One more important thing - could someone please share the experience with adding clients custom fonts? For a couple of our clients I wasn't able to add them since they are blocked everywhere, and I had to use pngs instead of actual fonts.