i think its more about being tricked into thinking a game isnt linear. for example: in cod in the first demo where they say "go flank them" i was like "yea fuck that" i ran out and killed all of them and half way through i got "mission objective failed game over" thats the kind of gay shit i dislike. one example that comes to mind is morrowwind, since it seems like you have so many options and all of them dictate the outcome, but thats only works sometimes because you dont want to be in the situation where you end the game and say "wow if i just would have done 1 thing different i could have had a different and better experience". the 1 thing i never want to feel after i beat a game is regret.
btw another good seemingly non linear game that i beat was shenmue. it wasnt as much about having options to dictate where the player ends up, as it was about every once and a while straying from the story line (arcades, mini games, jobs).
[i typed this while being up over 48 hours, so none of it prob makes any sense]