Vesper Crave Necklace: Is it worth the purchase?

My bf and I saw the necklace when we were browsing around for different toys. I think it looks fashionable and a little naughty if someone really knew what it was. I just don't know if it is worth it, based on how long the battery will last and how powerful it is. Does anyone have or had one and give me some reviews?

Thanks in advance!