Duodecim is just as good as Dissidia, the only thing Duodecim does different is offer even more fan service.
First the Story. It takes use into the action following the new characters, Lightning, Yuna, Laguna, Vaan, Kain, and Tifa and followed by Jecht, who appears to be a warrior of Cosmos.
Lightning- Lightning makes use of XIII's new battle system by being able to switch paradigms. Commando uses normal attacks to break the enemy by depleting there Bravery Points (BP). Ravanger is used to attack at a distance to combat an enemy with BP attacks from afar, both however have the same HP attacks. Medic gives her the ability to heal her BP points back, which is quite useful.
Vaan- For those of you who played Final Fantasy XII, will automatically pick up on Vaan's fighinting style his HP attacks incorperate the quickenings from XII (his awsome Pyroclasym make a return, yay). His BP attacks differ though taking advantage him being able to use different weapons, I've seen a Katana, Spear and Gun. Katana is slower but hits for my BP, the Spear is quicker and combo's more BP damage, and the gun allows you to hit BP away and also shove your enemies back in midair.
Laguna- is the distance attack hers cirle attacks on the ground use his machine gun and in the air it transforms into a Shotgun. His Aerial attacks help when your locked in close combat. the Ragnarok blade having a close range, it also is a rather powerful move. His satalite beam move allows you to attack HP from a distance, it also deals some BP damage as well.
Yuna- by far my favorite character to play as. The game works so well to incorperate her ablities into a fighting game. for instance Ifrit attacks for BP on the ground and Shiva attacks for BP in the air. Valefore is ground HP attack and Ixion is a aerial attack.
Tifa- her ablities take advantage of her style of fight. using her fists in both BP and HP
Kain- uses his lance and has ablities such as jump which deals damage to the enemy.
Another thing that dissidia does is give the characters different outfits, fans wil instantly recognize them such as Laguna dressed as the president or Yuna in her wedding dress. If you enjoyed the first Dissdia you should get it, if you are a final Fantasy fan you should play it. play this game reminds me of why I fell in love with the worlds greatest gameing series ever created. 9.5/10