Yes, it looks really good. I wonder if it will unseat Aseprite?

Not necessarily, ASE is has a smooth UI that people like and as long as you're fine within the constraints.

This one is great since it allows for in-editor previewing of "weird" ideas, I know I've re-invented that UV-mapping workflow shown with the skeleton on the page once for a game-jam and wanted to use it but skipped it in the end since asset-creation was "annoying", having support in an editor to preview it easily can be a game-changer.