Warning: the Sally Hansen Nail Art Pens work wonderfully. But...
They're easy to use, and they have bright, vibrant colors. What could be wrong?
They stain. Changing my polish wiped off the base coat, and the polish, and the design, but not the stain. This picture's base coat is two coats of China Glaze's Heaven -- and if you look carefully at my middle finger, you can still see a faint purple/pink flower. That's what didn't come off with the rest of the polish :( But it's faint, and the blue ones take attention away from the ghost of a magenta flower.
At least, I hope they do.
Also, I think they're cute.