I just wanted to put my two cents in here, not that anyone will actually read it, since it's on page 8. Also, I realize that everyone has their own opinion, but here's MY opinion of FF13:
I honestly don't know why ANYONE liked the battle system. It was WAY too simplified, and it actually punished you for trying to use your brain. All you did was use auto-attack, and switch your roles. THAT'S ALL YOU DID!!! There was no strategy, no thought, no control, and no fun.
The characters were horrible(except for Sazh. Sazh was pretty awesome. Except for the bird in his hair. I never understood that.) It's not just that they were annoying, it's that I couldn't relate to a single one. Not one. With six main characters, which is far too many, by the way, you'd think I would, but no. They just took some bad moral or ethical crap, split it apart, and gave it to the different characters at random. Hope(argh, bad name) was some whiny kid, who got scared and wanted to run away, or just froze up like an idiot. Sazh was, well, he was okay. Lightning was a cold-hearted *****, until she suddenly becomes Hope's new mother figure, and decides to be a good guy for no reason at all. Snow made me want to punch him in the face for being an arrogant bastard. He kept calling himself a hero, and then did very un-heroic things. He was completely annoying. Vanille was... an alien, I guess? I don't know, she seemed to be on drugs throughout the entire game. I hated her, too. And Fang was a cold-hearted *****, but at least she spoke her feelings out loud, which earns her some points, but that's it.
The story was... boring. It wasn't as complex as people were saying, it just seemed complex because they had strange ideas in it, but it was actually just a simple good versus evil thing, with a couple of boring plot twists.
Edit: Oh right, this isn't really an answer to the thread... hmmm... okay...
First off, make your characters less annoying. Since I like games with great characters the most, this would make me VERY happy. Also about the characters, cut down on the number of main characters to four or less. Anything higher than 5 and you can't develope the characters properly, and the players can't understand the characters' feelings. I thought this was one of the major mistakes of FF13. The only way that you could have more than 4 main characters, is if they were part of a series, but since Final Fantasy doesn't do that, stick with the four or less rule.
Story could be a little more clear. That's really my only gripe with that.
Oh, and better music. FF13's music was DULL. Better music would have grabbed my attention more.