Unmarked spoilers.

Playing through a second time I did pay more attention to all the hints that Kairi was with Sora. The first hint was when you enter Merlin's house, Sora saw Kairi walking around and talking to him. I believe that would be her heart speaking to him.

Also the way he said he recognized Hallow Bastion in the slideshow picture in Deep Jungle and when he first came to that world. That was definately Kairi in him recognizing Hallow Bastion, as that is where she came from. Also when Sora saw Kairi's memory of the old woman telling her the story of the keyblade in the Hallow Bastion library.

I'd have to agree it happened when Kairi flew into Sora's arms and disappeared into him.

As for Sora being a good hero, I agree with Giga Guess. He was acting like a kid because he is a kid. He's only 14, what can you expect. As far as the Kairi and Sora love thing goes, I wouldn't really call it that. There was definately a mutual attraction, but when they talked it sounded as if they were friendly but still unsure about their feelings.

Riku would have made one hell of a main character. If a game was made of Riku's story during Kingdom Hearts, I'd buy it in a heartbeat.