Yeah, it's "too good to be true". Grafting fruit trees is almost universal, but the key to a long, productive life is to match the top part (called the scion) with a compatible rootstock. This is a pretty exact science, and there are no "universal rootstocks" that work well for any scion, so some of the branches will do much better than others, essentially starving them because they don't have a good graft. Think of it like a body rejecting a transplanted organ, you need to find a good donor match.
Also, growing fruit trees in containers is very tricky in this climate, tricky anywhere really, but you won't get much fruit from a container tree. Fruit trees in general are prone to diseases and harder to manage than most people would guess from the beautiful pictures in the catalog. You need to be dedicated to spraying them on schedule (even if you choose to go organic, they still need some attention) and pruning them every winter.
I don't want to rain on your parade, but it's not a plant and forget it until harvest thing. You'd do well to learn a lot about raising whatever fruit you are interested in before buying your first plants. Some fruit really is pretty easy, if you know what to do and take care to do it at certain times of the year.
