Review (4/5): Overpriced but it does work
This is just salicylic acid in a small squeeze tube. It's definitely convenient and easy to use, but the price is a bit high considering that there are countless other identical products with the same active ingredient and concentration level. Salicylic acid works so try and find something cheaper.
Also, FYI -- wash your hands well if you apply it with your fingers, as this will stain/bleach your clothes and towels. I suggest applying with a cotton swab.