Eh, the pattern isn't much different from Final Fantasy 12's pattern of story-town-dungeon-town-dungeon-story, either. The 'corridor'-effect in FF13 isn't much different from FF10 either. The difference being that in FF10, the camera was fixed. In FF13 the camera is almost always behind the controlled character, accentuating the linearity to a greater degree than FF10 did.
I haven't finished the game yet (just made it into Chapter 12), but as far as the story goes, it lacks exposition. Whereas FFX gave us this unique world of Spira with a fish-out-of-water character like Tidus, exposition was easy to fit into the story and explain the rules and plights that govern Spira. In FF13, we don't really have a character like Tidus (though Vanille sorta fits this model, it's not played to great effect). So explaining the details behind the world of Cocoon and Pulse is difficult. It feels like enormous chunks of the story - specifically exposition pieces - were cut from the game and sidelined into the Datalog/Codex for players to read. I don't want to get into too many details because of spoilers, but there seems to be clear indications where additional story material would've sufficed to help flesh out the characters more and the world setting.
On the other hand, perhaps the way the story and lack of clear explanations with the setting is intentional. FF13 is a multi-part project, and they may be leaving intentional details out for the other games like Versus 13.
As it stands, Hope is probably the most real character. I know a lot of people tend to have a love/hate relationship with him, though. As others have said regarding Hope, he has very real reasons for how acts and why he acts that way. It's even better that he grows and develops through his issues - well before the story ends. He even gets more minor growth through after his resolutions in earlier parts of the story.
I wish I could say the same for other characters. Vanille and Sazh obviously develop more; though Snow is pretty one-dimensional and doesn't see (or really need) much growth. Lightning on the other hand, despite main character status, seems to become more and more mute the further the story develops. The last bit of development for her was near the beginning of chapter 7. This seems to be an issue for FF female protagonists. It may be SE's marketing or interior forces mucking up creative control, but this issue was the same in FF12. It's obvious that Vaan and Penelo contribute nothing to the overall story and that Ashe is the leading character. It seems the only reason Vaan is in the game is because SE didn't want Ashe to be protagonist for some misogynistic fear that players don't like playing female characters.
