Something tells me I shouldn't contribute to this topic, but now that I have read through the whole thread I feel that I'm obligated...
First of, to make things clear: I prefer a short, but great game over a long but mediocre game.
Secondly, when comparing absolutely great games, length comes into play. For example if you play an hour of Beyond Good and Evil and an hour of a 3D Zelda game, you'd say that both are equal. But if you play through the whole games you'll say that Zelda is better because it is longer and therefore more epic.
Because of that, I would love Galaxy if it would take me less than 20 hours to complete the game (not with everything) but it would not be a game on the same level as Mario 64.
Thirdly, if the extra stars are like in 64, getting all the stars means completing the game to me because it is a real part of it. If it is like in Sunshine were the extra stars felt tacked on way more, it doesn't really count to me.
But however, fact is, dear Legend11, you don't have ANY point. I bet you could find a user on a website that says he finished the game in X hours to EVERY game; reviewers are probably more worth more trust.