Are they worth the money? And how do they stack up against steel knives?
Ceramic knives' advantages include being completely impervious to rust, keeping an edge for a long time, and—since they're nonreactive—not imparting a metallic taste to food, JavaBean says on Chowhound. Given all of that, knifesavers thinks the best uses for a ceramic knife include cutting delicate things like lettuce (steel can discolor the cut edges) and high-acid foods like lemons. Otherwise, knifesavers says, steel rules.
And while a ceramic blade's edge lasts longer, it'll never be as sharp as a properly sharpened steel knife, timwaltham notes. You need a diamond sharpener for a ceramic knife, so when it gets dull you pretty much have to send it back to the manufacturer for honing, JavaBean says. Ceramic blades are also brittle—they can chip or even shatter. And though it's not a major annoyance, a ceramic blade won't stick to your magnetic, wall-mounted knife holder, ButterYum says.
Maybe keeping a ceramic paring knife around for cutting reactive foods is the way to go, Chemicalkinetics says, rather than investing in a ceramic chef's knife.