Well... it's not as bad as everyone seems to say it is, but it's certainly the worst in the series. (Yes even worse than X-2, which redeemed itself with the really engaging jobs and battle system)
Firstly the combat is wank. You can only control your party leader, while the other two members are controlled by the AI. The AI doesn't have a clue what it's doing, will constantly attempt to use physical attacks on enemies that take half damage from physical attacks, or will just randomly change between magic and melee on characters that have a terrible stat in one of them.
Speaking of which, there are only two stats, magic and strength, that's it.
You can change jobs mid combat, but that also comes with a massive amount of wasted time, such as your buff bots casting +strength on your magic users (a class which DOESNT HAVE a physical attack), using shell for physical only enemies or your healers trying to outheal poison rather than casting fucking Esuna.
There's also a mechanic called Stagger, whereby you chain attacks up and then it stuns them, allowing you just laugh manically at monsters as you just stunlock them to death over the next minute or so. It's broken as hell.
Speaking of broken shit, the AoE spells are horrific. Instead of the old system where you just cast them on All foes, in this one it's a specific AoE spell, (like in World of Warcraft or the like), which is great in action based games. But not in this, because you can't specifically target areas, just mobs, meaning they become obsolete over just blasting them with single target spells.
AoE Healing spells are even worse, because everyone moves about during battle, but you can't tell everyone to bunch up for a heal, or even telling them where to stand at all, and you will end up being spread across the battlefield, without anything you can do about it, crippling AoE healing to no end.
Furthermore there's no resources, so that's no MP, and you're healed and status removed after every battle, meaning you can actually play certain sections by just holding the stick foward and mashing X to use the games "Auto Battle" option, of which there is no point not using as you're just wasting time other wise, and you'll be fine, as it's not until the 19th hour mark that you even come up against a tough foe.
The levelling system is also horrendously designed. (Think the sphere grid from FFX, but then make it linear) There's unavoidable strength upgrades on people that can't use physical attacks, and granted one you get to the 22 hour mark you unlock the ability to make them use melee classes, but by that point you've already invested alot in their default classes, and the cost for unlocking these new classes is about triple more than what it is to continue with their already available classes.
The summons are horribly over designed, and downright ugly, it looks like Michael Bay designed them, right down to the fact that they transform (Seriously, Shiva is now two flirtatious twins, who turn into a fucking motorbike, WHAT THE HELL SQUARE?!)
Actually aside from the main characters, everything is overdesigned, it looks pretty I'll give you that, it's an FF game, they all look pretty, but in this one, everything is too busy and has far too much going on, like all aesthetic sense went out the window, seems to follow the design sense from Michel Bay. To quote Yahtzee "It looks like someone sat down to draw them, then never fucking stopped!"
Next, there is NO exploration, none at all. The world doesn't even feel like it connects as you can't go back on your self, and everywhere is just one straight corridor, with the occasional recess with a rubbish piece of loot. There are no towns, as they've been turned into Save/Shop points. The backgrounds all look very pretty, but function as wallpaper, rather than environments, instead you must stick to ze tube. There is nothing but the tube. There's not even any people, so the world never feels lived in at all, even in towns there's fuck all of anyone about.
The characters are /okay/, although the opening scene is blatantly trying to Ape FF7 with a character that is described by the designers as "A female Cloud", (and not just personality wise, they blatantly used the same facial model from Cloud in Advent children) on a train, with a black gun toting sidekick. Actually the whole opening scene annoys me. You've got Soliders gunning down unarmed civilians, people being taken to death camps, children being forced to pick up guns, and everyone is still all happy and cheery. It totally undermines the mood they were trying to set.
Hope is also inconsistent between battle and characterization, up until he undergoes his character arc. He's a wuss, shys away from fighting, and then pulls a boomerang out of his arse and busts through a military instillation. What the hell is going on?
I will say however, that the Voice acting is significantly better than it has been, it's still been noticeably dubbed, but other than that there's barely any cringe inducing moments. Vanille is the only one that sticks out as having a bad voice actor, she starts out from Brooklyn, then she's cockney for a bit, then finally finishes up in Australia.
The story is also all over the place, and while I don't want everything spooned fed to me, I still didn't find out the main goal until about the 19th hour mark. Even then its still not clear which side were supposed to be on. Up until that point, we know almost nothing, the exposition is put in an in game glossary, which are nice side things, but shouldn't be necessary to understand the world were in. Again, "you're supposed to weave exposition into the narrative, not hand everyone a fucking glossary!"
I only played it last month, so I went in expecting the worst, and I was surprised, I really WANTED to like it, and I slogged through it out of spite more than anything, but I still can't mount anything more than an over all, ughhhhh, about the whole experience. The game does make it pretty clear that the play should be involved as little as possible, while the AI and Auto Battle do any and all thinking for you. HANDS AWAY FROM THE FUCKING BUTTONS!
I think the thing that gets me are the people who love FF13, who really fucking love on it, and will pounce on you at a moments notice for saying anything bad about it. Even if it's just a rough criticism about certain things. Seriously, I think the battle system is awful, and you know what I get as a counter critique a lot of the time? "WELL THAT'S JUST HOW IT IS DEAL WITH IT!!!!11" Yes, I know that is how it is, I still don't like it, just because it is the way it is, that doesn't make it good.
Also, if I ever have to hear that fucking Leona Lewis song that seems to have been woven into almost every piece of music in the game, I will fucking murder someone.
Lastly Sazh is actually pretty cool. He's the only character that actually has a decent arc, doesn't display any strange schizophrenic behaviour and has the most consistant voice acting.
