Yes, the parallax effect on the background image is glitz. I'd argue, however, that the physic's engine is not glitz, but rather makes the device easier to use,

Yes, the parallax effect on the background image is glitz. I'd argue, however, that the physic's engine is not glitz, but rather makes the device easier to use, because when things work and feel as we expect it reduces the amount of mental effort we have to spend thinking about how to accomplish a task. E.g. when you can swipe a view to the side, and it 'feels' just like swiping a piece of paper to the side then you don't have to think about how to use the device, it all just makes sense. That's a smart design, minimalist in appearance, yet processor intensive.