I have never owned one but from reading reviews on a few kitchen knife forums and Alton Brown in his Gear book, they are not dependable or desirable. As already said if you drop them they will likely break or chip and are difficult to sharpen once they go dull.
Even the famous brand Kyocera I think says they are not a replacement for steel blades but an addition.
Save the money for a good steel blade and forgo them completely