I think it's a fair question to ask, Gimp is the one app I've heard being called a "Photoshop killer". In fact I'd only ever heard of Gimp before reading this, and the first thing I did was to google "Gimp vs Krita".

That said, Krita looks pretty good. I'm mostly using Gimp for drawing and I'd be interested in trying an alternative.

I like the simpler MyPaint, because its interface is very easy to use and I'm not (yet?) interested in the more technical parts of digital painting, I just want to draw stuff.