Metal needles like these are great for knitters who like a sharper needle tip, and they can also allow for faster knitting, since there's less friction between the yarn and the needles. For this reason, metal needles are often not well suited for beginner knitters.
Circular needles are great for any garment knitted in-the-round, as well as projects like shawls or scarves that are knitted flat. You can also knit a variety of sized projects on circulars using the Magic Loop Method.