Hm people keep saying this is going to be just like T1 but from what I've heard and seen there are lots of improvments/changes.
+ New Characters (never been a fan of this, I rather have like 12 different really well made ones, than 120 clones, but still it's a nice addition)
+ In-Game Transformations
+ Bigger and more stages
+ New combo System (With teleport)
+ Tag-team Mode (With Fusion and Special attacks)
+ Story Mode (can't wait to here more about this)
+ Updated GFX
+ Customizer (had no idea about this, but I've always loved customization, so this better be good!)
And there proably more to come, and more that I don't know about.
But I guess we'll just have to wait for more updates and for the game to be finished. ^^
The only thing worrying me at the moment is that all those basic ki attacks (those normal blobs everyone shoots), all look the same and even worse than in the first game :s. Probably just because the game isn't finished yet.