Very worth while.
Extremely tense scenes. Especially if the viewer has a strong sense of empathy..
Im not surprised to hear of people fainting and walking out puking.
Knowing it to be a true experience just emboldens the power of the horror in the situation further.
Sharp directing style from Danny Boyle, who seems to be able to accent the mindwarping aspect of the experience quite well.
Remember 'The Beach' where everythnig was visually stunning and the good times were rolling, then Wham! Shark atack and the mood is dark/nasty yet still retains its surreal aspects too?
More of that hard hitting dynamic switching which places you in the struggle by slightly warping reality here.