Do I lose anything when i update my Iphone 4's software to iOS 6.1?

I wanna know if I lose anything such as music, video's, pictures and apps if i update my iphone 4's software and what does iOS 6.1 do

Nothing will be lost. Just upgraded mine

Well, I updated my iPod Touch 4 gen to ios.6 and I didnt lose anything

No no no no no. It's a lot of bug fixes. You keep every thing I promise you.

You shouldn't loose anything. When I updated my 4GS I did a backup first. No problems.

You don't lose anything but an outdated OS: D