After buying it and using it for a few hours on Windows: Things I don't like - As you might expect for a version 0.5, there are pretty frequent crashes, which appear to happen mostly when expanding/contracting or hiding/unhiding a root node. Save often.
Things I do like - No installation required. No subscription. It's a bit like Workflowy and a bit like Treesheets (as mentioned previously), but I find it easier to read than either. It's fast.
As someone who suspects that they might have partial ADHD, I love that there are several ways you can put a "spotlight" on what you are working on (depending on the theme) - 1) Selecting more than one line causes other lines to be greyed out; 2) "Highlight" changes the background colour of the current line; and 3) "Focus" causes everything except the immediate branch to be hidden! So good!
Looking forward to the future and more stability. :-)