The cable "pops" into place.
This is caused by a couple of retainer indentations in the plug that mate with tabs inside the phone to give it a more secure connection. I can actually dangle the phone upside down while holding the cord, and shake the phone up and down with what I would estimate at a few g's of force versus the 30 pin connector that would disconnect in this position with a fraction of that force. One area the lighter iphone 5 helps.
One of the biggest advantages I've noticed in day to day use of the cable, is that it doesn't dislodge a little bit and break the connection like the 30 pin would. Example: if you pull the cord to one side, the 30 pin slides out a couple of millimeters and you lose connectivity, sometimes without knowing it. That's not going to happen with the Lightning connector. It goes straight in, and straight out, with not lateral movement at the base.