Juice FX is absolutely fantastic!!! So, SO SO HELPFUL in my GameMaker pipeline. I was exporting sprites into compositing software and animating them in there, but it was a slow and painful process. Juice FX was EXACTLY what I needed. 

The only thing I find weird is that the preview window doesn't seem to like anything except a square sprite. So for example if you bring in a sprite that is say 512 x 128, it will look distorted while you are working on it. But the final render is still fine.