KEEP the 1st person perspective - don't throw it out for 3rd person, or it will ruin the game. The immersion in fast running and jumping is what gives the game such adrenaline.
However, it would be cool if there was a "camera view" or "cinematic" button like when you drive in GTA IV so I could see her move from a 3rd-person perspective, and hit the slow-time button too. I'd also like to be able to have a replay button to see some of my runs again.
The story has to be better, explaining more about the totalitarian world Faith lives in. The city has to feel more alive, not just a backdrop. We have to care about what she's risking her life for.
Obviously, more stylish cutscenes.
Everybody knows the combat/disarming system has to be better. Too clunky and inefficient. I don't want to slow down to fight, I want to jump onto a Blue's chest, do a 90 degree turn and jump to the next roof while he goes crashing backwards through a window.
Take out the frustration - I got fed up with some of the puzzling "how do i get out of this room" stuff. I hated dying 20 times trying to string together the same series of moves. I probably would have stopped playing if I hadn't got the help of a walkthrough guide. A hint button, maybe?
Keep that music and design style - fabulous.
It's all about freeflowing speed and taking risks; running your ass off. And I loved disarming and then throwing guns away - it was like, "I'm so badass I don't even need this" - so although I want the combat system improved, I don't want to be able to do hardcore runs with a gun.