My handle knives were a few years old and dull. . .uncomfortable to use. I have a set of 12 knives. I looked at various stores for sharpening services and at $5 a knife it would be half the cost of this unit to sharpen a set just once. So I clicked on Chef's Choice based on the generally positive reviews. After receiving the device, I opened the box, looked through the instructions and immediately sharpened all of our knives. Developing "muscle memory” requires a little practice pulling the knife through the sharpener with the right amount of force and at the right angle. But after a few knives I got used to it. Our knives are now sharp enough and a pleasure to use again. After sharpening our set a few more times, I'll be in the black financially. Also, now that I have a sharpener, I can sharpen our most commonly used knives at will, which is a benefit of buying your own sharpener. linear scratches along the blade edges (parallel to the blade but a few cm above the edge), no doubt related to the blade being pulled through the sharpener. This does not affect function and is just a minor aesthetic issue. I didn't notice that with the smaller knives. If I had them professionally sharpened, I doubt I would complain about this minor issue if I received my knife back with scratches like this. But I noticed, so I wanted potential buyers to take notice.