Even with good diamond stones, ceramics can be highly problematic. Some, more than others, have too much of a tendency to chip.
At best, they require extremely steady angle holding, very light pressure and a lot of patience.
You don't want to use your coarsest, fastest stones, because it's too hard to polish out the resulting scratches and chips. And because their own harndess combines with the fineness of the stone to require so many strokes to do so little work, that puts an even higher premium on angle holding. Which, in turn, is even more of a problem at the higher grits, those where you produce a very fine, polished edge. Circular, and not a good circle either.
In my limited experience sharpening ceramics, the expensive ones (like Kyocera) are easier to sharpen than the no-name, cheaper, Chinese made knives.
Ceramics hold an edge better than any alloy I know of, true. And while the OOTB sharpness of ceramics is undeniable, they don't break new ground respect. In my opinion the user is better served by making and maintaining her steel alloys just as sharp -- not only because steel sharpens more easily without ceramics' tendency to damage during sharpening and use; but also because there's a far greater selection of knife lengths, profiles, and of good knives generally.
If, for instance, shroomgirl were to ask me which knives she should buy and how she should maintain them, after analyzing her needs I doubt my recommendations would include ceramics. But -- here's the important part -- she didn't ask. Presumably she's happy. And if she's happy, I'm happy. Ceramic knives notwithstanding.
Bottom Line: One should always use the knife which best suits. To each her own.
BDL