[Zwivix]

FM+ has a new weapons and You can fight all of the Organization again. All 13 members. There are a few new battles as well. And Cut scenes too. Sora has a new form( he changes into his old clothing from KH1)

http://en.wikipedia.org/wiki/Organization_13

Thats the organization member's names according to Wiki.

Also
http://www.kh-vids.net/

Here is a site where you can watch all the cut scenes from KH2 FM. There is a really cool one when Roxas first appears and Xemnas gives him his name. I thought it was cool.

There are also ALOT of videos of hacks. People making impossible battles ( Like playing as Roxas with Axel on your side facing Marluxia)

Also comes with a PS2 remake of KH: Chain of Memories

Ohhhhhh! And tanks for the video link ^^

As Secbro said FM+ has loads of extra stuff and a 3D ps2 version of Chain of Memories (on a bonus disc)
The audio is english for some cutscenes but all text is Jap.
And after going through cavern of rememberance (A super hard area full of super hard nobodies and heartless) you reach a room with white door all around you with a picture of a weapon on.
In each door is one Organization member, They are incredibly hard to beat, even fi you ahve final form on Max lvl and atatck them with it they brush you away with ease. If you go on the super hard difficulty One attack from Xaldin's Computer generated Version can kill you.
Axel's Computer version is really hard as flame on floor makes your health 1hp in no time

So its just a whole bunch of super hard extra stuff...