Campaign: Improve the camera! You don't know how many times I've died because of the awful camera. I would like to control the camera. Also the lock-on feature blows; it's annoying how it stays locked on to dead enemies. I kind of enjoyed scenario mode though.
Character's story should remain in Arcade mode, or at least have more than four matches. You get the prologue, fight two characters who are related to the one you're using, then you fight Jin and Azazel respectively, and the ending movie rolls. It was a step backward compared to Tekken 5. Each prologue had narration, and the stories had nice pacing. In stage 5 and sometimes in stage 7, you confront your rival or someone who is connected to your character (storyline wise), and a small cutscene plays before you fight them. I thought that was pretty neat. Also with nine matches, you get a good feel of the character you're using.
No more annoying final boss fights. Jinpachi was terrible, and Azazel is even worse.
More modes including online: like playing team battles online (not sure if you can).
Improve loading times.
No more ending movies unlocking without me playing the mode. I had no idea why the character's ending movies were being unlocked when I haven't even touched the arena mode. It kind of killed some of the replay value.
Agreed with the graphics, animations, environments and customization. Most of the clothing in customization are the same things but in different color, and it's ridiculous how expensive most of the things are. I also like more hair color selections. Asuka needs better clothes :P. Also, I would love the option to choose stage and music seperately in the main menu.
I'll try to come up with more stuff.
