Exactly what SeanHRCC stated, you have to be careful with what you change.
I, personally, wouldn't own an iDevice if it couldn't be jailbroken. Once done, you can pretty much do anything you want and from my understanding, it's a lot easier to restore an iDevice than it is to restore an Android.
I love the tweaks you can install and the way you can customize your iDevice to how you want it. You can go simple and just change the looks of the UI or you can get really intricate and change the overall functionality of it. Once jailbroken, it is basically at that point YOUR iDevice, not Apple's iDevice that they want you to have.