Each to their own IMO the air is far more comfortable to use than the ipad 4.as for the shape I don't understand what people are going on about and as for the music I cannot comment as the sound is going through my Bluetooth wireless speakers.
Owned 2 x iPad 2's and an iPad mini and the improvement of the iPad Air over the iPad 2 are massive, though saying that the iPad 2 still does everything the iPad Air does. I would not buy an iPad 2 new your better off spending that little extra to future proof with the A7 cpu.
I do prefer the size and weight of the ipad mini though,
The one thing i still do not like is iOS 7 its just not finished far to many bugs