Pros:Does revive ceramic knives which standard sharpeners can't do.
Cons:Expensive, slow process, doesn't work well with cheap ceramic knives.
The Bottom Line: A mandatory accessory if you want to use your Kyocera knives beyond the first wear. Not the easiest to use, nor guaranteed to work with all.
I own a set of cheap (no-name) ceramic knives and a set of (nice) actual Kyocera knives. Once the novelty wears off, the hype around cermic knives is certainly complemented with reality and a few shortcomings.
Recommend this product?
Aside from the (in some applications) impractically light ceramic knives, their superior durability is countered by the incompatibility with standard sharpeners. Diamond grinding wheels are mandatory for ceramic knives and it's often unclear if even a diamond coated sharpener is compatible unless it's spelled out specifically for cermic knives. Kyocera is well known for cermamic products and a such branded sharpener does indeed eliminate uncertainty, and yes, it does make it even more uncertain with the "... for Kyocera Ceramic Knives" adder.
To be upfront, my Kyocera knives are relatively new and didn't need sharpening yet, so the experience below is based on a set of three no-name knives which were not as sharp as the Kyocera fron the start, but got a lot of usage over the years ... enough to feel dull by now.
Of the three knives one kept chipping as I tried to sharpen it. In fact, i wasn't aware of chips before the attempt but in the end even repeated sharpening did not get rid of the chips and this particular kive was essentially ruined. Based on this experience, I'd take Kyocera's disclaimer somewhat seriously that it's for Kyocera knives only. However, the other two no-name knives showed imprvement and that that might make the disclaimer relative to certain conditions.
The instructions are to sharpen one side for 10 seconds (one stroke slow enough to take 10 seconds) and then the other. If the angle doesn't match, the sharpening takes longer as more material needs to be removed. Also, if the knive chips badly, it's even more material to be ground off and it becomes a questionable struggle between the knive and the grinding stone. (It's certainly not worth wearing the stones just to revive one knive.)
An easy to miss part of the instructions is also a very important one. As the process is slow, one might apply more force to speed it up. The sharpener is NOT designed for that and premature wear and potentially knive damage (chips) may be the undesireable result.
In the end, the sharpener revived the old knives just fine, but honestly not enough to compete with honed quality steel knives like the Zwilling Pro 'S' which I totally worship (with limitations like the price). However, for Santoku knives, the lack of heft may be the main reason why even the revived ceramic knives don't feel as good as my fairly standard 7" steel Santoku (Calphalon). In fact, the weight of large steel knives typically does the work for you while ceramic knives still need a bit more manual labor to get it going. Further, ceramic knives are not good for chopping ('hacking'?) where the lightweight blade is also prone to chipping due to the impact. Of course for completeness, ceramic knives should never be used for prying actions as they respond with a broken blade. All those are things a good steel blade doesn't worry about.
With the expense for the sharpener (in my case $50) and the limited ability to get 'any' ceramic knive really sharper, one might argue that a good set of steel knives may have an advatage as they tend to be heavier and easy to sharpen and hone.