Stem stitch is the little black dress of embroidery stitches. It is a bit more formal and refined. Certainly more dressy and impressive than back stitch, it is still a basic stitch that should be in every embroidery skill set. It is especially good for lines with gentle curves, as it handles the curves better than backstitch, but it is more difficult for sharp corners. It takes a bit of practice to get a smooth clean line, but it is worth the investment.