The thing that I've noticed is that while there are chunks of linearity (escape from the prison! Go through this dungeon!), there are a lot of sections of the game where you aren't obliged to do anything in particular. Go hunt some minibosses. Explore the land. Find new equipment. Go down this side quest chain. Etc etc etc. You _can_ just plow through from point A to point B and ram along with the story, but even with only 20 hours in, I have a bunch of things to do on the side when I want a diversion from the story.
Plus, there are reminders of where you want to go next in the story, which is nice for getting yourself back on track after fiddling around in the desert for a while. Some might complain that this tells you where you need to go next, but to this older gamer, the stuff I've noticed has been places that your character would _know_ without wandering aimlessly around their hometown trying to find their old friend Dalan's place.
Is it as open-ended as Oblivion? I don't know, really - that's an awfully high mark. But is it as godforsakenly linear as FFX? Not so far.