I use line2 with a jailbroken iPhone. I have never used line2 on a non-jailbroken phone so it is difficult for me to compare. But I can tell you that it still works. I think that incoming calls when your phone is locked might act differently, you cannot answer a line2 call from the lockscreen, not sure if this is different or not. Other than that everything works great, no enhancements with jailbreaking though.