I have, I couldn't get into it. Might have been a learning curve issue; Grease pencil also had a giant learning curve and I've only recently started to feel more comfortable with it.
But I just found Inkscape really awkward and clunky to use for any kind of illustration or free-drawing. I think Blender in some ways might have an advantage there because there are enough obvious cool features with Grease pencil (3D integration, rendering pipelines) that it provides more motivation to get past the "how the heck am I supposed to draw comfortably in this" hurdle. And it needs those motivators, Grease pencil is not comfortable to draw in without changing some settings and learning more about the general Blender interface; it's got a huge barrier to entry.
It's possible I could get Inkscape configured and comfortable to use, but I just didn't have enough reason to get over the hurdle. Or maybe it is actually too clunky to use more like a painting app; but I want to give it the benefit of the doubt since I'm less familiar with it.
