*SPOILERS*
I've made it pretty far into the game now, because I crossed the Calm Lands a while ago.
The game's really nice so far, and the gameplay is great; but the thing that struck my heart the most was the scene between Tidus and Yuna in that lake.
Yuna tries to hide her depressed feelings and talks merrily with Tidus about what they would do if Yuna abandoned her duty and didn't summon The Final Aeon; but then she starts crying, realizing that she must sacrifice herself for the sake of Spira.
Tidus gets silent, looks her in the eyes, and tries his best to comfort her - then "Suteki Da Ne" starts playing, while Tidus and Yuna are kissing each other.
This scene actually made me crying like crazy.
It's the most touching thing I've ever seen in a video game before.