I purchased one of these. It was well built but small. My issues were not with the product itself.
Just be aware though, when you are buying the modern mutant, red apples, they will not fit. And forget about any potatoes other than maybe small red potato.
You are right. Big apples will peel OK, but coring is a different subject. And the spear tends to wallow in the apple if a lot of pressure is exerted on the handle. A good compromise is to use the peeler feature and remove the corer/slicer feature. It should come loose with a pliers, as it is held on with a short hex bolt and washer.
I find that I use this a lot when the apples come in. Not such a good tool for other fruits and veggies.