Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Works well for a little while

I received a new knife that had a badly rolled edge on it. Rather than sending it back I decided to get one of these and re-profile the edge myself. This was a hard steel alloy (S30V) so I knew it would take some effort. By the time I got the edge back to the proper angle, the diamond abrasive surface was completely worn away. I got one sharpening out of it for 30+ dollars. I think the sharpener will work well for soft 440 stainless knives like you have in your kitchen or your swiss army knife for quite a few uses, but forget about it for quality knife steel. The adhesive they use to bond the diamond dust to the rods is not strong enough.