You can use Krita if you want to create illustrations or drawings not by modifying vectors (like in Inkscape) but by drawing with a digital brush. It’s pixel based like GIMP, which can also do digital drawing but with less ease and sophistication I imagine than in Krita. Whether it’s useful to you really depends on your illustration style, it’s probably less suited for a flat and vectory look. It’s more for things like storyboarding or other forms of digital painting.

From what I've looked into it, and now I'm a novice is it's build more for illustrations. I think of inkscape more as a graphics designer software for making images and logos and things which you might use for a company logo. Where as Krita is more artistic in nature so like paintings and things (web comics). At least that has been my thoughts from my minimal exposure to both. Though I'm sure you can easily do all in either.

Krita is more of a digital painting and artwork focused app. It can be used for raster editing or vector editing, but it is not optimized for that.

It is great for digital painting (that's what I know it for)