There are tons of answers to this question, all you need to do is to perform a quick search and so you will have an idea of what is jailbreak and what are the advantages of doing it.
I disagree! Typically, individuals who have decided to jail brake have not experienced any issues that can not be resolved. Jail braking provides a lot of options such as adding a theme, tweaking, etc. As long as one prepares by reading and researching, makes a good backup, and stays away from cracked apps it is, IMO , a rather safe path.
Worse case, do a factory restore and install the most current release of iOS.