I have nothing against QTEs per se, as long as they are practically used.
Currently playing God of War Collection on my PS3 and one of the QTEs that bugs me is the "button mashing" one which makes you stab a minotaur in the head or something. You have to press O pretty damn fast to get it right, which involves putting the controller in an unnatural position if you want to do it fast enough comfortably...all they'd have to do is change which button you have to press and it would solve the problem
Another is the "wiggle the left stick" one (which was repeated in the GoW3 demo), which I simply cannot do correctly with my left hand because of the placement of the PS3 left analog stick - if it was on the 360 (with the thumbsticks in a more comfortable position) then I'd have no trouble.
And a major one that I hated on Heavy Rain was the "shake the controller" one which, in order to avoid repetitive strain injury, I could only use hand one for...and often you'd need a "stick sweep" or button press right after a shake during a fight scene, making it even more awkward.
On SW: Force Unleashed the QTEs were one button presses which I have no problem with (and even the button mashing parts didn't require you to hit the button as fast as in GoW...plus it was a better placed button to mash). The only problem with FU's QTEs were that the on screen prompt distracted you from the cool finishing moves you were performing in the Jedi battles.
I do like how in GOW3 the prompts are positioned on the screen as they are on the controller - so even if you're not familiar with the layout, you know that when it appears on the left, you press square, on the top you press triangle, etc. And they don't interfere with your view of your awesome finishing move.
Anyway, my point is that having to change the way you hold a controller does not make a "challenging" QTE, it means it has been badly designed.