I found the ending really shocking, it moved me in a way I've never had with a game, before or since. Yes we knew Tidus' fate, but because it was so vague I kinda didn't expect it to actually happen. I thought perhaps something inside of Sin, and his Father, might have caused him to carry on living. But then that twist came and he started to fade away, and the realisation that it was true and Tidus was going to disappear. That, coupled with the
Ebm version of To Zanarkand in the background (Uematsu you steal my heart every time

), and it wouldn't matter how much of a toughnut I am, I just burst into tears. I couldn't hold it in. And with Yuna falling through him, saying "I love you", Tidus giving her that last hug and then accepting his fate with such pride. Yuna is left to rebuild Spira without the one she loves, and the whistling brought on a fresh burst of tears. The only thing that kinda spoiled the moment for me was seeing Rikku jumping up and down waving, what the hell? Tidus was going away forever, I don't think she really understood the gravitas of the situation.
But as shocking and sad as I found the ending, I was happy with the way it went. As it's been mentioned before, too many happy and anticlimatic endings, this was really refreshing, and the emotion it brought out is also testament to the fact that it was genius. Everything became so clear at that point.
Excellent ending, and again I agree with you all- then comes FFX-2 to spoil it. Stupid fools, they shouldn't have tampered with a masterpiece like that.