Just chiming in with an observation. Was in the Apple Store today and happened to show the sales people (3 of them looked at it) the vibration issue and they all said that wasn't normal and I should make a genius appointment. One brought out an Air 1 as a comparison and mistakenly thought it was an Air 2.
I then went and played with the demo Air 2s and they all vibrated to one degree or another. Just goes to show you the "expertise" at the Apple Store. The people selling apparently have never used the products they are selling.
I didn't actually talk to a "genius" as the place was mobbed and I didn't feel like waiting there.
they are trained monkeys to repeate the same sentence "that is not normal". have you ever heard anything else from their mouth when you are complaining apples product? "this is the first time..."
althought the vibration is heavy, and it is vibrating from the start you turn the volume on just for the single step, you get used to it on some level. it feels funny, i dont like it all and i have noticed that i place my hands upper and upper all the time avoiding the vibration.. and im keeping the volume only on 1-3 bars =P