Hi, I do not know if that is what Riot is aiming for. I hope they are trying to make Diana similar to the old Akali (but fair).
Diana will be very similar to the old Akali if her ult does not do a lot of damage, but pulls units in, stealths Diana and does damage when she reappears. Diana would need to learn to pull enemies in one direction and run in another (it will not be very bad because Diana will not be able to use it in every fight). Either that or some sort of stealth mechanic, would increase the learning curve, make playing her more interesting/fun, give her a way to escape/play mind-games and emphasize her utility.
I hope Riot would consider it.
Edit: I think Diana's Q could have the same speed (or something similar) of her original Q. Opponents would dodge it a lot unless maybe if Diana is skilled.