I've used one type myself on another Honda model that was _badly_ deteoriated. Much improved, but not perfect. The degree of improvement will depend on how much work your willing to put in to the polish aspect of the job and how far gone they are to begin with.
He sells a nice plastic polishing kit, and I think the buffing compound is the missing link I did not use to really break down those sand marks. I saw the Insight recently who's headlights I sanded and polished and they still are looking pretty good.