Highly recommend Expel over newly polished headlights. I brought mine back as described by others here, but within months they would start to get hazy, although nowhere near what they originally were. Local guy custom cut the film for my headlights, and I applied them. $50 for the film, $100 if he applied it.
I am totally impressed! Two years have now gone by and they still look new. Going to cover wife's SUV headlights next. Great stuff (and there are other similar products from other mfg's).