Saw them live tonight here in PHX. Was a very good show, and they played all the songs I required of them, except for CANDY GIRL and MARLENA. The other one I wanted to hear a lot they did play-BEGGIN'. The show was good, and they played for over 2 hours. I don't know Frankie's age, haven't looked it up. The Four Seasons were all young guys, but they did a good job of backing him up.
If you like his music, he still does it well, and there was a lot of exuberance in the performance. I was told one of the original Four Seasons was the primary song writer for their hits. I don't know his name.
I just googled Frankie Valli. the mofo is 80 effing years old!!!