People compare Krita to Photoshop, and that's fine. There's another space where it shines and people might not know about that. It's animation. Friend and I have been working on a hand-drawn short animation (~10 minutes) for a few years now and it's just about done (final stages of sound editing). We started out in Harmony, but we were extremely disappointed with it. We tossed around the idea to switch over to TV Paint (raster based), but I thought that maybe there's an OSS something for it? Being an OSS fan and advocate, after all. If Toonz were released earlier, we might've tried that (not really, considering years of experience with it). We even considered Photoshop - it now has a nice animation workflow built-in, but I didn't want to go away from OSS until I explored all the options. So, there was Krita. Let me tell you, not only is it great, it easily cut down our animation time by a large percentage over if we were using Harmony. It's awesome tool for 2d hand-drawn animation with still A LOT of room to grow, workflow-wise.

tl;dr; If you want to animate by hand, give Krita a chance. It's better than Harmony and Toonz (again, for hand-drawn animation).