I brought these as a stocking filler a couple of years ago, and they were worth every penny.
The "glitter" is mostly just window dressing. You cannot see it when the lights are out, but the stars themselves are very effective. They last 2-3 times longer than most of the competing brands that I've used (I filled an entire ceiling up with different sizes and shapes).
They are even much more light sensitive than the other brands, too.
I put them in a room with a cable TV decoder, and they keep glowing for most of the night purely from the light on its display and some light that comes from around the edges of the curtains.
They also glow 2-3 times more brightly than the other brands that I've used. If you mix them up, you can clearly see which are from this packet and which are the cheaper Chinese brands.
The light that they give off is greenish yellow rather than white, but it's very soothing, and doesn't cast any shadows that could spook children.