I wasn't a big fan of the characters myself. Sazh was the only one I really gave a s*** about. Then again, I also didn't hate any of the characters, even Hope. Of course, everyone outside the main six and Serah had pretty much no development, which kind of hurts the story when we don't give a s*** about Cid or the villains.
13's problem with linearity is that it didn't even really try to make the world look anything more than a tunnel. FFX was pretty linear as well, but the towns and dungeons were designed to seem large and open. FF13 is almost nothing but tunnels, like you're going through a rollercoaster, except you're constantly interrupted by five-minute random battles.
13 also didn't really have any distractions from the main gameplay. 7-10 had minigames like Blitzball to break the monotony, while 6 and before were fast-paced enough to get away with it. Even 12 offered large worlds to explore and hunting sidequests to take a break from the plot. 13 has nothing but plot to go through, so it just dragged on for me. The 2D games were the same way, and even the exploration was artificial and the sidequests sparse in 1-4, but at least those games had pretty quick battles and managed to convey more variety in their one dungeon tileset than 13 did with its beautiful corridors.
In the end, my complaint with 13 isn't that it was linear, it's that it was mind-numbingly repetitive in a way none of the earlier games were, which is kind of a feat considering what series it's in.
And I have no clue why I wrote this, but I wrote too much to just discard it now.
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