Somedays they're the cats meow, other days the may not finish with them. I think they really help get the attention from distant fowl. I've had different experiences with them, sometimes they want to land right on top of the spinner, other times they want nothing to do with it. It's another tool to have in your arsenal though.
One addition we started on all our spinners a few years back is buying the remote for them so you can control it from the blind. We'd sometimes turn it on for just a few seconds to get their attention and shut it off once they'd located our spread. Food for thought.