I would say the fact you can just press a button and be in the camera and then press it again (with half press functionality) to take the picture. However I think Microsoft have a patent on turning the screen on by pressing the camera button so an Android phone is unlikely to gave it.
Going from a Touch HD with no camera button to an Omnia 7 with decent two stage camera button is night and day, one of the big things I'm umming and raring about with the S/X...![]()
The Xperia S has great camera functionality. All of what you've mentioned there and more.