Yeah I really loved the first game. People tell me KH2 and BBS are better so I'm really excited. Didn't like CoM all that much. Played until Neverland and watched the rest on youtube. Days was awesome though
Really depends what you are looking for.
My favourite of the series is KH1 but despite it's similarity with KH2 in many ways they are totally different games also. Well the best thing is that if you liked KH1 and could stand the Days ''movie'' you will probably love KH2 too.
KH2 is also a weird beast because the Final Mix rerelease adds so much cool stuff and improves the base game that even some of the harsher critics of KH2 give some more credit to it. Sadly it was never released outside Japan until with 2.5 and even the fan translation was released very late so most hard core western fans were forced to go with no KH2FM at all or struggle with menu translation notes and such.
KH2FM is the most modern feeling game of the series certainly and the combat is most fluid, fast, flashiest ect. Feels like proper evolution of KH1 combat, quite big improvement even if I don't agree with some of the magic changes and totally useless summons. But even magic has some nice twists added so you can combo them and cast them while on the move if you have one of your magic heavy drive forms on. Drive forms are likely the most fun addition to the combat, it basically makes your character go into super mode and totally change the way your fighting style works. Like the most basic ones being Valor and Wisdom form. Valor form allows you to dual weild keyblades and move very fast and it's super fun if a little button mashy. Wisdom form turns your basic attack into projectile attacks and let's you cast magic freely while moving at the same time. Long story short the combat is really fun and smooth in KH2 and definite improvement over KH1, especially with faster camera that isn't quite as close to your character. Also the air combat is much more prominent than in KH1. Gummi ship segments are also MUCH improved over KH1.
But the stuff that KH2 falls short frustrate me even more so since the core ''game'' part of it was really pretty much everything I was hoping for and what they promised. The story part of it is one of the more prominent ones that get shat upon by critics. I don't hate it really like some people do but the one thing it does have a problem with is pacing which could have been really easily fixed to make more better flowing main story. Disney worlds do some pretty cool stuff but unlike KH1 where they were the heart and soul of the game and really connected to the main journey in KH2 mostly feel more tacked on (with few exeptions). They are a ton of fun still but I wish they really poured their love into binding the both universes.
The map design is much more linear and with fewer sidequests and little secrets to find but KH2FM improves on this. One of the biggest dissapointments was lack of any cool post game content but FM totally fixes that and adds 14 high level optional bosses to keep you interested after finishing the game.
I think perhaps the closest comparison between KH1 and KH2 would be DMC1 and DMC4 or something like that. My favourite as I said is KH1 but I still love KH2 (especially FM) very much, one of my favourite games ever no doubt. Also KH2 (the vanilla/original) is actually the favourite of the fans in the west if you go with some old polls and general discussion and FM adds much on top of that so you probably can't go wrong with KH2.
BBS (FM) is really great when it comes to handheld KH games. Really fun game and unlike CoM it plays almost exactly like 1,2 with more traditional action RPG approach. Some really cool ideas too on this one but it also has some problems that I think some of the biggest fans of this will notice when replaying it on the big screen and supposedly compare it to KH2FM that is part of the same collection. Really fun game tho and an exeptional game when you think that it is originally made for PSP that was released in 2004.
