I am the slowest cook on earth, and this is mostly because it takes me forever to prep the veggies. This speeds things up considerably.
It comes with a variety of blades, all super sharp -- great on very ripe tomatoes, even! And it is cleverly designed to store all the blades in one, neat package. I also like that you can adjust it to cut the slices in 3 or 4 sizes. It is wide enough for a huge bell pepper I had to dice today for stew -- I set the slicer on the largest setting, and it was just barely big enough to make some small "dices."
It has a veggie holder that makes sure your veggie is held securely and reduces all risk of cutting yourself--a mortal fear I have always had, and the reason why I have not bought a mandoline until now.