I agree with Skyblade and Del. I'm not looking to spend hours bashing my head up against a brick wall until the wall eventually crumbles. I don't quit as the OP suggests, though perhaps I should. The euphoria of winning is great, but it doesn't outweigh the frustration I've felt over the past hour or two I've spent having my trout pushed in by a broken boss like the Locust Queen at the end of Gears 3. I come away feeling unsatisfied overall, not accomplished.

Trial and error is fun if implemented correctly. When the error is punishable by having to restart a lengthy sequence again then no, I don't think that's the way to go about it when designing a game.

A perfect game difficulty to me is having winning on the first attempt, but having a really tense back-and-forth battle (just as an example) and getting by via the skin of my teeth, one tiny piece of health left, I am a God. On a replay of the game, perhaps I can get through the same area unscathed by surgically eliminating the enemies one by one because my own skills and knowledge of the game are at such a level where that feat is capable.