It’s a very good app suite that gets the UX right esp if you use multiple of their apps but it falls short in areas that Adobe has had more r&d money thrown at, such as vector tracing, proper vector brushes, and proper psd support (you can import psd files, you cannot export fully editable psd files). I used it myself for branding and UI design for a few years and it’s definitely worth the money, but they do have some issues as I’ve said before. Their file format isn’t open source either afaik and there is no plugin support so it’s a friendlier looking and cheaper closed ecosystem.
Depends with what you might want to achieve, some people will say inkscape or gimp. In my minimal experience while they win in some departments like plugins and features their UX and UI is really not as good, but that’s just how it worked for me, some people would swear by them.
