No, not at all. All it will do is void any warranty you have on the PSP.
While the PSP gains the ability to illegally play copyrighted media, keep in mind most PCs can do this by default, and there...
Custom firmware allows you to do things on your psp that you wouldn't normally do. Like playing gameboy games on your psp. Made by psp hackers its your choice whether you trust them or not. If you do...