I had a gourmet peanut butter cup from a boutique chocolatier, and it was like a flashback to my childhood, eating Reese's on Halloween. It's entirely my subjective experience, but it convinced me that they changed the recipe at some point in the last 25 years or so.
I'm partial to the nutrageous bars and the pretzel big cups, but yeah regular Reese's cups just aren't as good anymore. I think the base ones are just too oily anymore...