I know I'm WAYYY too late for this thread, but it makes me genuinely upset seeing KHII torn into so much. I absolutely agree it had it's glaring issues with it's story, but Kingdom Hearts as a whole is no stranger to that problem. but calling it a trainwreck? maybe a bit far. of course opinions are opinions, but I'd just like to offer my extremely late one.
now, as far as the rest of the series goes, here is my list of best to worst. gameplay wise:
1.KHIIFM. the gameplay of this one was damn near perfect for me, personally. fun as hell, although WAY too easy usually. exception being on critical mode, where it was still fairly easy, but provided a great challenge. very very fun, mostly balanced very well. worlds were memorable as hell although infamously being basically themed hallways. still, a few stand out to me such as pride lands, pirates (requiring different strategies w magic and stuff), olympus coliseum, hollow bastion, and space paranoids, among others. cavern of remembrance was definitely a step up in complexity and design, though.
2.KHFM. the platforming, although clunky at times, was such an integral part of this game. I really, really miss it in the later games. world design was BY FAR the best in the series. so many secrets. puzzles. actual incentive to revisit worlds and explore them. combat was still pretty fun although clunky in its own right. magic was more diverse I think, and it was actually used for other things in worlds themselves. needing different elements and upgrades to your magic to unlock certain chests or areas. so perfect.
3.DDD. although I haven't played it, the world's seem a little bigger and more explorable than in previous games since KH1. also flowmotion looks super fun. I've heard balancing is sorta an issue with balloon and stuff. I'm not too fond of command decks either since BBS. which takes me to...
4.BBSFM. although balancing was HORRIBLE with surges, mines, and ignite being basically the only viable options, it was pretty fun and the different command styles were pretty fun and flashy. normal combat definitely took a back seat which I really didn't like from it. worlds were kinda boring. overall though, not too bad.
5.358/2 Days. worlds weren't super memorable. neither was gameplay, besides dual wielding roxas and it was incredible being able to play as the organization members, although it was pretty limited.
6.re:COM. so many people hate on this game. it did get very tedious at times and it was endlessly confusing, but it was unique and it was fun seeing all the different sleights and combinations you can do. I also really liked the sorta customizable worlds with the different cards. so overall, pretty dumb combat but it had its moments. worlds were neat.
7.Coded.not much to say since I haven't played it myself. looks pretty uninteresting.
now, onto story.
1.KHFM. nostalgia aside, it's where it all started. no convolution, no overcomplexity. well, for the most part anyways. seeing SDG's relationship and bond form will always be one of my favorite arcs from the series. everything felt connected, more straightforward while still maintaining that mysteriousness that we all love now from the series. Sora felt way more special and his development was so good. he was so much more focused but he still had the childishness and yet bravery that he's known for. Riku's arc was equally (if not more) as amazing. Kairi, although still kinda portrayed as unimportant, at least felt more important than the other games. Sora was just as concerned with what happened to her as he was Riku, and as a Princess of Heart, she was pretty central to the plot. I could go on and on about how great the story was in KH1, but I've made the more important points.
2. KHIIFM. although many would disagree, I think this is one of the best games in the series story wise. it obviously does have its problems with complicating things a bit. like, completely changing the identity of the previous games final boss just because. or adding in so many more forms of darkness and introducing the organization. I really, really do hold a special place in my heart for this game, and not just for nostalgia. the intentions and purposes of certain characters are explained. also, Riku's arc is fleshed out which is definitely one of my favorites from the series. in the second part of the game when the organization kind of blackmails SDG with the collection of hearts is very well done, if not kind of confusing with the arrival of Days. the Disney worlds didn't really tie in as much with the overall plot which sucked, but it's alright in my eyes as they aren't always meant for that purpose, even in 1 (although it did do it noticeably more). but overall, I think it was a pretty strong story with a few big flaws.
3.CoM. although a notoriously disliked game, I thought the story was very strong. definitely darker, but I like that. it was very emotional to me, seeing the rising need to get higher in the castle to avoid losing every memory they've ever held dear. I loved seeing the dissent within the castle's org members and how they had their own motives and stuff. and this game kinda brought back the disney world involvement in the plot which I was happy to see return.
4. 358/2 Days. Roxas is definitely a favorite of mine and I liked the format and pacing of the story, going day by day. things grow very dire and I loved how serious things got towards the end. definitely had its problems as always, but good.
5.BBS. definitely changed things for the worse in the series, in which I noticed the complexity starting to get a little too ridiculous. I did enjoy the relationship between TAV although it did seem a bit forced at times, as if they really weren't as close as the game wanted us to believe. the story felt kinda hollow, for lack of a better word. things didn't feel as connected or dire as they should've been. I did quite enjoy seeing the interaction between each character in the worlds and their subsequent visits. it made the worlds feel at least a little more important. I liked the ending too, seeing each character's fate and interaction with Xehanort was interesting and dismal.
6. Coded. don't know a thing about it. something with computers and data? I've heard only the ending is important.
7.DDD.haven't played it yet, but all I've heard is that Sora is dumber and there's time travel. that sounds like a recipe for disaster. I don't have high hopes, but I'm sure I'll still enjoy it.
I absolutely love all kingdom hearts games, but some are indeed better than others. sorry again for how late this is.