Yep what Ren said. I didn't have the FP one, but I had an unsettled reflux baby and found it to be a godsend if I needed a short period of time to do something.
Didn't find it changed her sleeping habits at all (though her's were non existent anyway).
I got rid of mine which I'm a bit sad about but I was worried what Darcy would do to a baby 'trapped' in a swing lol.