I got these for my daughter with her brand new scriptures for her baptism. I didn't realise how much of an effect they would be. First, it was a good opportunity to show her how to look up the scripture reference (going to the front of the book and looking at the contents page etc) Second, one of her favourite stories is Samuel the Lamanite and she was able to look it up because the sticker was there. It actually encouraged her to read (she struggles with motivation for reading).
You have to be careful getting the stickers out. I had a few, rip a little.