Originally, I didn't want to go. Not being particularly religious, it seemed like not my cup of tea. Heard that you should get a tour since you get a lot more information. Not only that, but you get to bypass the huge line out front. Everything comes to life when someone explains what it is and where it came from and the significance of it all. The church basically stole most of the treasures promising eternal life in a good place. Selling indulgences at the highest level. Such corruption. Such greed.
Ironically, these treasures exist now because they were warehoused at the Vatican. The sheer number of items, not counting books and manuscripts is enormous. I can't remember what the guide said exactly, but if you spend 10 seconds on every item you would spend 1000 years doing it.
Huge statues (many male parts removed by Pope Innocence or covered by leaves), Nero's bathtub is the size of a room (25 foot radius) made out of one piece of marble, tapestries.
We were only there for a few hours and barely scratched the surface. Definitely worth your time for a visit while you are in Rome.