Is it bad to jailbreak your iphone 5?

They say it avoids your warranty how would they know if i restore my phone before taking it to them

It is not bad it is awesome. It will void the warranty, but they can't tell if it was jailbroken if you reset it, so there's no problem at all!

Yes and no if you do it voids your warranty but say if it breaks while its jailbroken if you restore it and bring it to apple they'll fix it jailbreak does some much awesome stuff i can't even begin to start

The jailbreak will still be left in your systems hard drive so yeah it does void your warranty but there are benefits to jailbreaking, such as being able to customize your home screen and keyboard and get free games with installous (which is the illegal bit to jailbreaking) So it may void your warranty but there are many things you can do with a jailbreak but if you are planning on giving it in when a new version comes out our something don't jailbreak