I mostly do "line drawings" on little maple "plaques" with rough edges and such. Birds, flowers, etc. While I agree with Stacy that it isn't a "high art" difficulty, it does take attention to chiseling the lines in smooth and proper depth. It can get more advanced blending lines and such by tapering one line against another so there aren't abrupt ends showing and such. I enjoy it.
I've seen really elaborate inlays in two and three colors of wire and several thicknesses done on boxes and such that blow away even the great stuff we see on some knives.
It's easy to do ugly, but, like Stacy says, it's definitely a practice-improved technique. I've seen as much done poorly as I've seen done well.