I beat FFX-2 a while back and have been meaning to post my thoughts on it, so here we go!
I avoided X-2 like the plague for years and now that I've finally decided to actually give it a chance, I think it's actually a pretty good game. Not a good story but a good game.
Started with stuff I liked, the game play. There's a lot of good ideas in here that I kinda wish Squeenix would revisit. I like having access to the airship from the get-go. It makes the game feel open ended and I like that no matter where you go there's almost always something for you to do there. You could probably dump a good four or five hours into the game before your even tackle the first mandatory story mission.
The battle system is a ton of fun, and I feel like XIII took notes from it but did it wrong. Switching jobs mid-battle is a neat idea that allows for a number of different strategies. The way it ties into the garment grid is really neat. I like how each grid provides different passives, actives and boosts allowing some great character building options. On a side note, I like how the characters change costumes with they change jobs (not the animations, I ended up turning those off, but the concept). It reminds me of FFV, which I imagine this game took some inspiration from.
I do have a few criticisms, though. First, the game introduces the ability to climb on ledges and jump around from place to place. You'd think that this would be used to create interesting and exploitable areas but since so many of the game's maps are recycled from FFX it ends up getting extremely underutilized. Second, is that this game is laughably easy. Like, this is probably one of the least challenging FF games I've played. Even if you don't use the extremely powerful Special Dresspheres you can blow through the game no problem. The challenge does ramp up suddenly at the very end of the game, however. But at that point it just makes the difficulty curve feel like you're running headfirst into a brick wall.
Now let's talk about the story.
Oh boy, never in my life have I felt like a sequel misunderstood its source material as badly as X-2 does. Before I rip into the story, I will confess that it does have some good sequel moments. My personal favorite scene is when the Gullwings visit Zanarkand and Yuna is applauded that a once sacred site has been turned into a tourist attraction (It's like someone on the writing team actually remembers that Yuna was once an extremely devout woman!). There's also the matter of different factions rising up and fighting to fill the power void that Yeven left after it collapsed, which would make for a fantastic sequel but it horribly out of focus for really stupid reasons.
The story's got some neat concepts, but focuses on all the wrong places. The game presents us with the previously mentioned Youth League VS. New Yevon VS Machine Faction story but instead chooses to put its attention on cheesy treasure hunting antics. Then, suddenly there's this guy who looks exactly like Tidus who wants to activate this giant robot that will blow up Spira, and both the treasure hunting and factions stories are pushed aside for that. The game then awkwardly bounces around between the three stories until it ultimately settles on the Tidus-Look-Alike story.
This is a major problem, it feels the game doesn't know what it wants to be. IMO the best story here is the factions story, since it focuses on what a squeal should: how the world reacts the the events of the first story and the repercussions of the character's actions. Unfortunately, since the first third of the game is focused on treasure hunting antics, is never as developed as it should be. There's a part near the beginning of the game where you have to give a sphere to either New Yeven or the Youth League. The game treats this like some kind of moral dilemma but it falls flat on its face because the faction story is so underdeveloped at that point that you feel like your choice is meaningless since you have no idea what these factions are and what they stand for.
My biggest issue wit the story is the Shuyin plot. As I mentioned before, the guy looks exactly like Tidus and wants to activate a big gun to kill everything because his lover was killed during a major conflict long. My main issue with this story is that is it not a very good sequel story, but it effectively puts the potentially morally complex faction story on the back burner for a generic "new threat" kind of story. Although my biggest gripe with the Shuyin story is that it is never once explained anywhere in game why he looks like Tidus. From what I've read, the director says that it's a "coincidence." This pretty much means that Shuyin's appearance is to give Yuna motivation to pursue him. This effectually means that Yuna is a woman who supposedly cares deeply for Spira and its people but the writer's can find a way to motivate her to help unless her lover is involved and CHOO CHOO ALL ABOARD THE UNFORTUNATE IMPLICATIONS TRAIN!
That brings me to my final issue with the story: characterization. In FFX, Yuna was a very religious woman who cared deeply for the well being of Spira and was willing to sacrifice her life to protect them. Even when she found out that her religion was a sham she never gave up in her steadfast desire to protect the world that she loved, looking for way to deal with Sin. Suddenly, in X-2, she's basically be turned into little more than a thief who can't be bothered to get involved in the larger world unless there's some profit tied to it (admitted, this aspect of her character seems to change from scene to scene). It doesn't help that she's gone from being quiet and thoughtful to playful with an attitude. The worst part is, Sqeenix knows that she's very OOC in this game and has every character comment on it.
Poor Rikku got her characterization butchered to make her fit into the "dizty girl" archetype. This irks me in particular because Rikku was one of my favorite characters in FFX. Seeing someone who once had competent leadership and craftsmanship skills, as well as smarts with machines and even some level of diplomacy despite her quirky personality suddenly running around like an idea spouting nonsense and being too stupid to understand new kids Shina's intentions is just jarring beyond belief. As far as other characters go, Paine is a horribly generic produce of the times, the faction leaders are very forgettable and I don't think I've ever hated a FF character as much as I hate Brother.
TL;DR version: FFX-2 is a solid game, but a horrible story.