I tried voice commands for a while but honestly I never liked the idea -- it annoys people around you, and it is as difficult as selecting by hand while driving - which of course I never do.
More and more manufactures are not including the physical SEARCH button, and it looks like Google gave up on the idea in apps like Market where the search magnifying-glass icon is prominently on top. Also, the Android 3+ tablets are missing all the physical buttons, which I personally miss a lot. Samsung Galaxy 7 tablet has all 4 buttons, but Galaxy 10.1 already does not have any.
I think as the voice recognition improves the button may come back, but for now only simple commands work and Google Voice mailbox is sometimes comical, everyone call me and says "Hello Auntie!"
