It’s ok, although there is no undo/redo. Sure, there is an undo all, but if you made one minor mistake and don’t want to restart, you have to choose white. Other tools it is missing include:
•Color Picker (there is a limited number of colors you can keep in the little color palette to the right - if you accidentally color over a color that has been erased from the color palette, you have to get a close estimate, which can be hard, annoying, and usually noticeable. This also goes for a possible undo/redo button that doesn’t erase your entire image)
•Eraser (in case the coloring over mistakes in white shows up)
•Paint Bucket (not required, but easier than spending 2 hours filling something in)
•A background so you can tell what is white and what is blank (most art softwares use a white and grey checkerboard or a solid hot-pink background to signify what is blank)