FF XIII is probably the most painfully linear experience I have ever had. A lot of games are quite linear of course, but the design of the game might be such that you at least feel like you're in a vast world, with things beyond, only there is something hindering you from getting to those places. There is an illusion of freedom.
For 2/3 of the game I never got that sense at all. I felt like I was in the land of OZ, following the yellow brick road to the Emerald City. I really did feel like I was just following one path, going from A to B, from cutscene to cutscene.
What made it even worse was the way the game limits your control over the battle system. It's a good battle system, but your ability to utilise it is seriously limited for half the game.