Ceramic knives offer a number of advantages over traditional materials like stainless steel, not just the extra sharp edge. Ceramic is immune to many types of corrosion, and will never rust. It's also quite easy to clean, and won't discolor or change the taste of foods.
On the downside, ceramic knives are rather brittle, meaning they can chip or snap, whereas steel will become deformed. Ceramic knives are not good for prying, and it's not a good idea to drop them on the floor. Of course, this goes for all knives, so just be careful with them.
Many ceramic knife manufacturers recommend using ceramics for softer things, such as slicing fruits and vegetables, and keeping a set of stainless steel knives for other purposes or heavy duty use. But the edge will stay sharp for quite a long time, especially if it's used only on soft things, which makes them a favorite of chefs of all sorts.
Find some more info on ceramic knives and pick up a set today: