So I haven't found a thread here on the forums.
Well then, this ought to be the official thread for Kingdom Hearts 3D.
I'm going to start off with a few impressions from what I've seen so far (spoiler-free of course):
Gameplay:
The combat system is loosely based on what has been used in the PSP installment of the series, Birth by Sleep: You get a "deck" of combat commands which are divided into three groups: Special attacks, magic and items. Like in BbS, there are no MP and the commands need to recharge before they can be used again (except for items where you get a fixed number of the concerning item which goes down every time you use it and automatically restocks when you exit combat). Over the course of the game, your deck's capacity will be extended by defeating bosses or winning other special fights (possibly even mini-games though I am yet to come across one of these). Other abilities, such as the high jump, glide or block/counter abilities are found in a separate part of your deck.
The first novelty is the "free flow action system", which is activated by jumping against a wall or other objects and pressing the Y button. By pressing the Y button again, you can zip around and do REALLY crazy moves. If you press the A button while in the free flow state, a special attack can be unleashed (which is usually friggin' strong).
Up next are the "Spirits". They are one of two kinds of "Dream Eaters", the critters that run around the game (enemy Dream Eaters are called "Nightmares") and you can raise them to be your companions in battle. This can be accomplished by entering a sub-menu in the main menu and selecting "create Spirit". To create spirits, you need to gather materials which can be found in chests or by defeating enemies. There are also rare Spirits which can be created by using rare materials. After the creation, you can move them into your party where a total of three Spirits is available. To raise the dream eaters, you need to feed them special food found in the game or play a mini-game or just pet them. You will be given "Link Points" which you can use on the "Link Board" to get new combat commands or abilities (like Combo+, Ice Boost or HP Up). To use these, the respective Spirit needs to be in your party – something I think kinda sucks because if you switch Spirits, you need to gather Link Points again to get abilities you already had back. Fortunately, Link Points are shared between Sora and Riku and the two can also use the same Spirits – so there's no need to create separate Spirits for each character. In combat, the Spirits attack the enemy or use their power to aid you by giving you positive status changes such as Protect or Shell. Attacking also fills up their Link Gauge which – when it is full – enables you to use the Link command via button shortcut or touchscreen. You can Link together with either one or two Spirits and the results are different for each combination of Spirits and character – Sora performs a Team Attack (e.g. swinging a Spirit like a morning star) and Riku absorbs the Spirit(s) to get a power up like the Blade Aura from BbS.
The third defining gameplay element is "Drop". While playing the game, the Drop Gauge next to your character's portrait fills up. When it is full, a countdown starts and after that, you will be taken to a menu where you can trade Drop Points (which can be acquired by defeating Enemies) for bonuses (e.g. a deck command, stronger attacks or a slower Drop Gauge) and munny (the game's currency). Then, you get to play as the other main character. You can also Drop by using a symbol on the touch screen in the main menu or in the pause menu during combat. While it is necessary to Drop from time to time (or you'll be unable to advance the story), it can be somewhat irritating during combat, especially since your foes' HP are back to full once you switch characters again – if this happens to you during a boss fight it means you need to repeat it. You can however prolong the time you can play with one character by using a certain item while the status effect sleep (or the usage of certain techniques) speeds up your Drop Gauge.
Plot (no details):
The plot itself takes place after Kingdom Hearts Re: Coded. While it may seem necessary to have played all its predecessors it is actually not. The game comes with a full glossary of all important terms, character profiles and even summaries of the previous installments. So basically it does not matter if you've skipped a Kingdom Hearts game (I skipped Re:Coded) or are new to the series altogether, you will still be able to understand the story fine.
Tech:
The game itself looks good graphically, in fact, I'd place it among the best-looking 3DS games so far, right next to Mario Kart 7 and Kid Icarus: Uprising. However, Square still managed to put in one of the mostly encountered technical problems within the franchise, namely frame rate slowdowns. Despite not being as extreme as they were on the PS2 (Kingdom Hearts I & II had some serious frame rate drops, especially when you defeated enemies that dropped great amounts of munny), you will get some slowdowns when fighting larger groups of enemies.
The sound is overall very good, despite not always employing Disney tracks (so far, I've heard only one background score taken directly from a Disney movie), the VAs are also good (in my opinion, the english version of the characters is the best of all) despite missing lip synchronicity.
I will post a final impression when I'm finished (which may take some time) but all in all, I can really recommend this game. That is unless you strongly dislike Kingdom Hearts or jRPGs altogether. But everyone else should really play it.