I have had the Zyliss safety can opener for about 2 years, so I know it pretty well now. I am not easily impressed and get very disappointed when products do not live up to their claims, having said that, I have nothing but praise for this product.
Let's compare how can openers works. Other openers either cut inside the rim, with a blade that penetrates into the can contents or cuts beneath the rim on the outside of the can, again penetrating the can. Both of these methods tend to contaminate the cutters with food, necessitating cleaning of the cutters, ideally between cans as well as at the end of the task.
How did Zyliss overcome these problems? Their opener neither cuts inside, nor outside below the rim, but outside around the centre of the rim.
Why is this so different? First the cutter never comes into contact with the can contents, so a wipe over with a damp cloth is generally all the cleaning it needs. Secondly the lid is simply lifted off after the opener is removed, there are no sharp edges to cut you on either the lid or the can.
Now we come to the bit I really like, because the lid comes off so cleanly, you can put it back on. Why would I want to do that? If I am cooking a meal in the oven and need to heat up some beans, peas, spaghetti etc, I give the tin a good shake, as the contents will have settled, take the label off, paper is a good insulator and I don't want that in the oven. Next I remove the lid, then put it back on, the whole thing goes in the oven for about 20 minutes and I have an instant oven pot, which just gets thrown away, not washed up after use. Remember; "Efficiency is educated laziness".
The opener also works well on the rectangular corned beef cans, but does distort the straight edges a bit.