I don't know...
I may be in a minority for this, but I can't do twitch gaming that well. I got to a point in Resident Evil 4 where you have to do a series of button pushes during a cinematic in order to "live" through it. In theory, it's not that hard... they show you the button and you press it or the right combination of buttons.
But I screwed it up. And any failure during the long series of prompts, and you had to start over from the start again. Over and over. I was livid by the 30 minute mark of retrys and had to walk away. And I was very upset with the game afterwards... especially when it gave me a series of position sensitive survival button presses just in the next area that held me up for another few minutes... no I didn't realize I had to walk away from the back wall before the lasers came if I even wanted my button press to do anything at all. I'm bitterly grumbling even now about it.
Anyway... a difficulty spike, even if it's not a problem for some, with no way around it can really put someone off a game they are otherwise enjoying immensely.