I just find the whole immersion concept unfounded and varying from person to person. Of all the things that could "break the immersion", I think the most prevalent would be your immediate surroundings and the fact that you have a controller in your hands(or a keyboard).
I disagree fully.
I find it very immersion-breaking if I'm in a tough fight, and just as I'm about to kill the enemy - I suddenly switch to a movie-like camera-mode view where time is slowed and you see the enemy die.
To force the player to change from the point of view (3rd/1st person) into a movie-like camera-mode view, while slowing the time; is very very immersive-breaking to me.
Because of what I stated I above, I simply hate it. On top of that, I find it unrealistic (it's pretty obvious why it's completely and utterly unrealistic).