Well, I should qualify my statement- I hear differences in environments that I can control- the only 24 bit recording I have done, and been able to compare to 16 bit is using my digital multitracker, so it is in my basement, where it was controlled to the best of my abilities.
But, I don't know if it is necessarily that it sounds "better" - my goal in taping is to most accurately reflect what it really sounded like when I was there. In achieving that goal, 24-bit is definately better, to my ears.