Chapters 1 through 10 were compeletely linear. Well, 10 started having the normal 'side rooms and alternate passageways' that they really should have had all along, but still pretty damn linear.
11 (after a short sequence where hope gets his eidolon and there are lots of pep talks all around) puts you in the middle of a giant field. A field full of enemies of varying strengths. HINT: The large, menacing-looking enemies are NOT EASY. I'm pretty sure some of them aren't possible, although I bet if I talked to people half of them would say they were able to smash everything in the area without breaking a sweat. Because that always happens.
And instead of a main plot (I mean, I *guess* there's a main plot, but the waypoint is impossibly distant, and there's no one chasing you and you don't have any real goals, which is really the problem the characters are facing, since they're on a time limit) (you're not, though) you've got this series of quests given by floating... quest giving... things. That run you around in all directions.
So if you were wondering if the world was ever going to open up... yeah. @.@ Boy, does it ever.