The phone is held by a happy balance between the magnets and the lip, but I guess my Plum didn't have enough lip at one of the corners and I had to push the phone back in every once in a while. The benefit is that the silicone case is easy to put on and take off.
Hmm, one corner for sure lost its magnetic connection, so would a sudden jerk propel the phone out? Maybe, but you would have to be making sudden strong movements with the phone in your hand. I think the Plum that I returned was defective and it seems this year's cases were rushed out. I didn't exchanged it because for some reason(s) I just didn't like it. It's not bad, but in the past I would just buy a case and I was done and happy. I wouldn't care if I learned another case was better because the one had was good.