Is jailbreaking your iPhone 4 safe?
It becomes really slow and things you download from Cydia can never be deleted unless you completely restore your device, which takes way longer than usual
Yes 100% safe :)
Jail breaking your iPhone 4 is not safe. This is because it will lose its stability and safety. Your jail broken phone may get locked out and the apple support group will not provide support or warranty to your phone. Visit http://www.lifehacker.com.au/2011/05/4-reasons-not-to-jailbreak-your-iphone-ipod-touch-or-ipad/ for more tips.
Its a risk you take but as long as you dont download anything too shady it should be fine
i prefer unlocking it