Ready to enter the bowels and intestines of a giant whale....
...Yeah, me neither.
Sam and I make fun of Riku a lot, but I like his character a lot. As it goes on, he does progress and becomes one of the more interesting characters in the series. We'll see it later on as we move into Chain of Memories and onward, he'll be used to explore some of the more complex themes that Kingdom Hearts explores.
Even now, he does serve as a good example of how to write meaningful, and believable characters that grow over the course of a story. He's not out to be a bad guy, but a number of critical flaws and some miscommunication have squared him against our hero and turned him to the path of darkness.
I joke that he's like Sasuke, but in truth he's a league above that Uchiha edgelord.