8*/10*
Its one of the best free and open source pixel art drawing software ever. Although some functions are not polished, its really nice if you don't want to buy Aseprite.
the main problem is that it will take 30 minutes to getting used to but its really powerful.
One thing I miss is:
tool such as shape drawing are missing although you can do shape with brushes but it wont support click and drag to change its size.