What are the pros and cons? And is it worth it?
You lose absolutely everything. But you do gain a bloody costume part, and at P3 you have a small bonus percentage to gain better items in the Bloodweb. Your items, addons, offerings, and perks will all be gone, and you will have to acquire them all again.
This, realistically it's better to not prestige not even for the better P3 Bloodweb stuff and if you have a bunch of perks unlocked it's stupid how hard it is to even get your own uniques again.
Besides P3 usually either gets you dodged or tunneled and camped by the killer.
All right thnx.
Strictly speaking, no. It's not meant to be worth it, it's just there to give the people who play hundreds if not thousands of hours something to do. You get a set of cosmetics and a very slightly better chance to get higher quality items in your bloodwebs, and that's it. It's entirely optional.