Just downloaded this to try it out, it feels great! There are some things that bother me with it though. Mainly, even though i have a retina display (on a MacBook), the app opens in low resolution, which makes the fonts look awful, and there seem to be some kerning issues as well (irregular spacing between letters), especially with smaller window sizes.
Something else, which may be a bit harder to fix, is that if i resize the window, i get black bars on the top/bottom or the sides. It would be nice if the writing window tried to fill the whole window (while still keeping its aspect ratio), while the background would zoom to cover the whole window.
I’ve also attached a screenshot so you can see the kerning issues, hopefully you get what i mean. It’s especially noticeable in these example letter combinations: lly, hile, it, ill, le, uld, alle.