If I run this on my phone that is loaded up with apps and music, will it damage anything ? I've always wanted to jailbreak but didn't want to risk messing up my

If I run this on my phone that is loaded up with apps and music, will it damage anything ? I've always wanted to jailbreak but didn't want to risk messing up my phone. I also heard jail breaking it causes your phone to become unstable and crash. Any truth ?