Well, my reason for jail breaking my devices is added functionality. For example, "Miwi Fi" on my I phone. For the iPad, programs like "I-file" are also great. Honestly, It all depends on what you want to do with your devices. Many people also J/b there devices so they can pirate. Others jail break so they can totally customize their phone. There is something for everyone when it comes to jail breaking. You just need to find out why you want to jailbreak. My suggestion is do, play with it, and if it's not for you, restore and your good to go.
Tom