Easy to use, could have some improvements though.

The interface and interaction is just great. After you learnt how to use every functions, its really easy and enjoyable making a pixel art.

Some suggestion for improvements:
1. Have smaller previews. Currently the preview is several times the original size. It would be really handy to be able to preview them in 1:1 sizes.
2. Custom canvas size. For example if I want to create a 18x18 pixel art, Ill have to use the 32x32 preset and manually draw a border in the middle.
3. More editing tools like lines, rectangles and circles. Its rather difficult to create a shape of a certain size. So having tools to create different shapes in a specific size would be nice, especially for circles.
4. Multiple color palletes, like bookmarks. When creating pixel arts with kinda "grindy" looks, for each color there would be different variations. In this case multiple palletes would be handy.

This app is really well made, and with more addition to functonalities, it would become a great tool not just for doodling, but serious pixel art creation as well.

Shiyuan Zhou about Dots (Pixel Art)