I have seen these during the last few visits I've made to a HF store.
Today I went to buy a couple other things and decided to get a knife too
(the medium-size, $11 one).

I've been aware of ceramic kitchen knives for years, but when they first
came out they cost a fortune and I didn't care enough about kitchen
knives to want one. The idea of a ceramic being tough enough to make
into a thin knife blade is fascinating though, and the HF knives are so
cheap that they're only ~2X what a decent steel one would have cost--so
I decided why not. It is odd how you can see the shadows of your fingers
on it when you hold it up to a light.

I have already heard that one requirement of these knives is that they
cannot be stored where they will rattle around with anything else (that
is, in the drawer with most of the other knives) since the edge will
chip easily. Also you can't pry with them or strike anything hard.

After getting home and getting it out of the package, I noticed it
doesn't seem very sharp. I haven't tried cutting actual food with it
yet, my assessment of "not very sharp" is just scraping my finger on the
edge, and slicing a couple pieces of paper. The plain steel knives I
normally use can be honed sharper in 15 seconds, and a new razor blade
is WAY sharper. Is this normal for ceramic knives, or just for a Harbor
Freight knife?

Second, do you sharpen these things? I have a couple diamond knife
sharpeners around but I would assume even the finest of them to be too
coarse. ...Since you're not raising a burr, the grinding would have to
be a very fine texture. I would guess the best way would be some
mirror-finish/optical diamond polishing compound and a sheet of paper or
similar. I don't have any diamond compound around and a tube would cost
$16 from Enco, so I would be spending $16 to sharpen a $11 knife. :P

Lastly, is there any kind of food that ceramic knives are especially
good for cutting?