We run promoted listings and get a lot of impressions but not a lot of clicks. However, being a newer shop trying to gain traction, I think it's worth it for us to get noticed. Plus, you only pay for clicks, so we seldom hit our daily limit. I'm sure more established shops will find more success from it.
I do find it much easier and better than the old search ads, which we didn't have a lot of experience with but didn't like how I had to set up specific keywords. The promoted listings will automatically pull in your new listings and keywords.