I tried this with a dent in my passenger door, and it DID in fact help the dent a little. It was creased anyhow, but this helped make it a little less noticeable.
Never worked for me, I had a ding from a door(not a sharp dent a little one) nope. tC had a dent on a crease and I knew from the get go it wouldn't work. Crease dents require a pro to take out.