I had no expectations going in and came out blown away at what I just watched!!
Now I was not a huge four seasons fan (not even a big musical show guy), but did enjoy the music. So I would say you had to at least "like" their music if you were to live this musical.
What made this musical so great was a combination of acting, singing, stage direction, and great story line. The guy that played Frankie vallie sounded JUST like him, it was amazing! Whomever wrote and directed this was a genius, because the show moved along so fluidly and kept you intrigued every second of the way.
I've since watched a handful of other top vegas shows, and this remains my all time favorite.