when pulled horizontally is hard to unplug ... when pulled in an angle is unplugged easily ... seems like physic works but i did not have any issues .. !
I have been using my new Air in the same ways as my old rev A Air and 08 unibody MBP. I have noticed that the magsafe2 is constantly falling off unlike my original magsafe. I am not hitting it, mainly lifting it from the foot stool to my lap on the couch with the cord running towards the floor. Almost every time it will fall off. I wish they had kept the old 90 design.
I think the older design, while more secure, was also more likely to not release if, for example, you tripped over the cord. They seem to have erred on the side of making it easier to disconnect versus easier to throw your laptop onto the floor.
Mine seems just as secure as the original MagSafe on my MB Pro 2008. If yours is unplugging without any friction on the cable, you may have a bad unit (computer or charger).