I really had to create an account for this (sigh). First post here we go.
You people are really unfair to The_Echo, he is untitled to his opinion like anybody else. He just responded to an opinion with his own (as difficulty is subjective and all, on a small scale). Gotta keep respect going ...
That aside, I am one of the few that liked KH II more than I. Yes, it is flashy, but that is not all there is to it, at least for me.
Story:
KH I's story is simple (we can all agree on this I presume) but simple =/= good, the main villain (Ansem SoD) was just dropped out of nowhere, and Sora was oblivious to everything that happened for most of the game but still won at the end ...
I would say KH II's story is more complex than it is convoluted, and it makes sense for the most part (looking at you Namine). The nobodies were a natural thing to me (as KH I states the heartless are made from hearts, we even see a cutscene in traverse town at the beginning, so I always wondered what becomes of the body and here we have the answer). I actually prefer puzzly stories that require me to scratch my head a few days before making sense of everything, that may have something to do with it. Some people also complain about the Ansem/Xehanort reveal, saying it was an unnecessary twist, but what makes more sense: someone refered to as a wise man by his people (leon and gang) randomly "turning to the dark side" or an evil (more overcurious than anything) apprentice turning on his master and stealing his name? I'd take the latter ...
Gameplay:
KH I's rather sluggish and slow whereas KH II is fast paced and more fluid. Nothing much to say here as it's obvious which one's on top (I think).
A few things though: the horrible camera in KH I really ruined the platforming aspect of the game (I'm not a fan of platforms to begin with ...) and the form abilities could have been used better in KH II, but at least FM has the cavern of remembrance.
I didn't like the trinities (no love for the world specific party member, and too much backtracking: it took me hours in game and minutes on the net to find that last green trinity in wondrland that i totally forgot ...) nor the dalmatians (just another form of treasure chests).
Keyblades:
Most of the keyblades in KH I lost their utility by the end of the game, in KH II however the abilities linked to them make them usefull even postgame, this even makes decisive pumpkin the top damaging one with combo boost. It's not really the keyblade's reach that's wrong in KH I, it's Sora's reach ... more than once I swung at air, but maybe that's just me.
By the way, TAV's keyblades are not the same ... for example Terra's ultima is longer than Aqua's ultima which is longer than Ventus's ultima (this is what The_Echo was trying to say ... I think)
Difficulty:
The cause of all this turmoil ...
KH II is easy, but so is KH I. As it was already stated KH is not a game meant to be hard (on normal at least). Against mobs KH II is a press X to win, and KH I is a spam X and thunder.
I just finshed my final mix/ default equip/ low level run/ no continue run on 1.5 (+staff, -shield), and it was rather challenging; however the Mp rage/ Heal/ Leaf bracer combo makes Sora invicible and I could just tank the last boss (with aerora on) and heal when necessary ...
"Reaction commands make the game (KH II) too easy" I do not really agree with this statement, to me they just made each boss fight unique and memorable, and there is no fight you can win with just RC (exept for Xaldin, but that's the whole point of his battle: block> RC). Reflect is a game breaker, this I can agree with; this is why I didn't use it against the data battles and lingering will, so I can enjoy the battle more.
Difficulty is not really a matter though, as you can just decide to challenge yourself to your liking (no magic/ limits/ drives/ damage, initial equipement, low level, lv1, ...). Looking forward to my KH I lv1 run (but that last heartless wave at the EoW though ...).
Magic/ Mp:
I must be the only one who disliked KH I's Mp system (don't shot me down!).
KH I's Mp was abusable, you can use all the magic you want and never run out, because the lower the Mp, the easier it is to refill (which leads to heal spamming) and every "3/4 rooms" ther's a save point to refill the Mp. In this regard, KH II is worese as you can just heal> wait> heal ...
In an actual fight though, KH II's Mp system is better as you cannot spam magic, 1, 4-5 castings and you have to survive a limited time without magic.
However, I never had to use a single ether in both games (personal experience, no belittling meant). So, I'd rather have a system where the Mp does not refill IN ANY WAY (exept for item use of course), which would add to the difficulty too.
Disney:
"The disney part is integrated better in KH I" to a certain degree yes, to me the only parts of disney that's integrated to the overall story line of Kingdom Hearts are the princesses of Heart, Mickey/Donald/Goofy/Minnie/Daisy/Jiminy/etc, and Maleficent/pete, ... all the others are not as important. This is why I want to see the princesses return to the spotlight in KH III (and they should, given ddd's ending).
Storywise, the relevant worlds in KH I are traverse town, wonderland (princess), deep jungle (that argument between Sora and Donald was pretty much needed to reaffirm their motivations), agrabah (princess), monstro (puppet> heart thing, foreshadowing ddd's reveals), neverland (Kairi!), hollow bastion, and Eow.
The relevant worlds in KH II are twikight town (Yen Sid's tower is part of this too I guess), Hollow bastion/ Radiant garden, Space paranoids, Land of dragons (Riku?), Beat's castle (to a certain degree), disney castle/ timeless river (to me at least as it involves Maleficent's whereabouts), TWTNW, most of the revisits (though optional).
I think a revisit of the world, with original stories is a good thing as it gives incentive to replay the worlds (other than grinding and synthesis material search). And I want them to come back ...
In KH I, SDG were looking for Riku, Kairi, and the King, everything else just happened around that, at the end, only Kairi was saved ...
"In KH II SDG had no goal and were just wandering around" Not really they were still searching for Riku and The king which is why they needed to open new path to search for other world (killing heartless and nobodies along the way, being a keyblade wielder and nice guy on top), and the organization had other plan for them. Which is why Sora was moved by finding Riku (with Kairi it was just a "what?" face, because she was suposed to be safe you know?), he attained his goal after one year ... I don't understand the people seeing gayness here.
This turned out to be more like a rant as I was typing because of all this "KH I is wayyyyyyyyyyyyyyy better" hype.
Well, to sum it up, KH II has it's flaws (story incoherences for the most part, nothing gamebreaking) but I still like it more than KH I (too simple a story for me, many lingering questions about Ansem's whereabouts and stuff, not so great gameplay). I realise I am one of the minorities but at least we can agree that everyone is untitled to their opinions?
Well, thanks for reading this man's thoughts. And I apologize for any misspelling I overlooked.