Have been using the app version recently and it's pretty good !
I really wish there was a way to stop the kind of "Auto-layout" that happens everytime I add a Quad or an Image tho, because if I want to add something after I have exported the atlas and worked with it in Blender, it destroys the layout and I have to readapt everything :c
Edit: And a way to resize evenly the quads in the Atlas, if there is I haven't figured out how to do it
Edit 2: And a way to rotate 90° an atlas quad :D