This is the best free pixel art tool I've used! It's definitely worth at least 5 dollars, it feels really polished and looks nice, but there are a few things that could be improved.
Customization would be nice, I find the cursor a bit intrusive, and I would like to be able to move on screen elements such as the color pallet or tool bar.
A straight line tool is necessary for good diagonal lines, it's an essential part of most workflows, so that would be a great addition.
There also need to be a selection tool to move around clusters of pixels on the canvas.
Besides those few nitpicks, this is a really quality tool that I hope gets more recognition in the pixel art community!
Edit: I've found that the straight line tool is bound to shift instead of being it's own tool on the hotbar.