As an artist, I enjoy the ability to create digital illustrations with ease. There are many different brushes and tools that are necessary for those who like to make digital art and digital paintings. It could be used for logo creation and other illustrations for graphic design, but I would suggest using Illustrator instead, since it's more about precision compared to Paint Tool SAI. Paint Tool SAI feels less limited compared to Illustrator, so I like it more. A final bonus for the program is the ability to have custom brushes, and change settings for brushes.

I like how accessible this program is. It's easy and intuitive to learn compared to Photoshop, because this program is specifically for painting and doesn't include different photo-editing tools I will never use. There is a color wheel that you don't have to dig around for, there's a transform/rotate type tool to let me see the design from far away, and there are many different custom brush sets that are easy to download and implement. It is also much cheaper than Photoshop.

Not so hard to use, if you have experience with other drawing programs, getting used to SAI won't be hard, ease in creating and customizing brushes, and my personal favorite, how easy is to rotate and invert.