I've made a couple posts on my opinion on the game:
To be honest, 358/2 has a bit of the CoM syndrome, you grit your teeth and bear through the annoying parts (CoM: basically replaying KH1's entire plot, 358/2: Mission after mission of killing heartless) so that you can see the cutscenes and story unfold in the scenes afterwards (CoM: Events on each floor of CO, 358/2: Ice-Cream scenes, Org Member meetings, Xemnas shit), but those cutscenes/plot as a whole make the experience worth it because it's heart-wrenching deep/introspective/dark shit.
The game is absolutely gorgeous for a DS game, it's probably one of the most fantastic looking games on the platform, and theres hardly a pinch of slowdown in even the most action packed battles. It is a genuine transition of, I would say moreso KH1's battle system than KH2s, but it was pulled off very well (the only decrepancies people seem to have is with the camera controls, which aren't that big of a deal)
In terms of difficult, it's hard to place.
-You lose HP FAST, which means you're close to dying a lot
-Enemies have a LOT more HP, they're not negligible punching bags like previous game
-You don't have immense combo ability, you have to be mindful to time your attacks and know when to dodge/back-off an enemy
However,
-Healing items and abilities are plentiful
-Enemies don't do a whole bunch in terms of smartly attacking you, they kinda wander around
-You may not have the power in your attacks, but limit abilities and spells are WAYYY powerful and kill stuff really easily in a pinch
Like I said before, gameplay is enjoyable and a genuine KH experience, but the progression of the game is so very much repetative. HUB world, talk to Saix/Xemnas/Whoever, get sent to a Disney World, walk around and kill Heartless (sometimes boss) until this little 'Heart meter' fills up, and then you walk back to the portal and the day ends. However, I would say that once the game is in English this may be much less of an issue if, at the veyr least, we'll be able to understand what every Organization Member is saying, and enjoy the experience for what tidbits into their lives we'd be able to take from that.
The ability system is fantastic. I just know that this is just a one-shot deal and we won't see any semblance of it in future KH games, but I think I'm going to miss it slightly, because it is very fun. Basically you have a grid-panel attributed to each character, and your abilities are sort of like tetris-block formations that you fit into the grid until it's "full", and that's basically your character progression. Magics are leveld up by lining up combos of the same type of spell on the grid, what Keyblade (or "Gear") you wield is based on equipping a certai level of "gear" and what adjacent abilities are touching it, which morph it into a new keyblade. Also added is the Critical Hit system, where you have a certasin % chance to do a stun-enducing tons-of-damage attack to a Heartless.
Multiplayer is pretty much the bees knees. Every character feels very unique, and each character has their own individual "panel" system like I mentioned above, so you can completely customize and build your Organization Member to your specific taste and give them abilities that compliment their traits. Organizatin Members also get unique weapon changes, which is a really small detail they didn't need to do but went the extra mile to, including fantastic "Joke" weapons like Xigbar shooting lasers from a Hair Dryer, or Axel flinging spicy pizzas. Also, there are a good number of unlockable characters that everyone has wanted to play as in the past.
So, 358/2 Days is a very enjoyable mixed bag.
-The gameplay is great in terms of controls and the battle system, there just isn't very much to do with it besides battle a bunch.
-Game is a technical feat for the platform, but just being selfish, you kinda wish there was more things like voice-acting and FMV scenes
-In terms of story, even in the little tidbits we've heard the story is probably one of the darkest and touching in the series without even knowing the whole thing and necessarily how it all unfolds. However the story seems, for now, entirely isolated and self-contained, so there's not very much sense that the fact that all this ever happened is reflected in the other games, so it's disappointing in that sense.
-Multiplayer is very fun, but local-play only, and each individual player needs to have a copy of the game...so, if you can manage that, awesome, but I doubt a lot of people will :\
