So, they just up the difficulty? There are no special items or anything that you can access on your second time through?
I've done Easy- Insane difficulties(I was going for that cool avatar of N7 that yo get for completing the game on Insanity...apparently its just for the 360 *cry*).
The difference between difficulties is insanely obvious. One, you and your sheilds take more damage as you go. Secondly, your weapon does less damage or your enemy has better shields and defenses. And most obvious, in harder difficulties, enemies move around more like a tactical group. They move in groups from cover to cover to keep you from pinning a single target. They also try to surround you, and more notable still, they use abilities. Particularly Immunity, which gives them INSANE protection from damage(Took me 10 minutes to take down the 2 Krogans in the Breeding Facility tunnel just after the bomb was set up
Also, they'd never need to dumb it down for Shooter online. You could still keep the same level up and upgrading element, but just apply it to the online element. Mass Effects shooting and combat system is good enough, they'd never need to change anything to make it a great online shooter, IMHO.
Favorite Line: Tali: So Liara, all this exploration of lost Prothean technology is just like a regular adventure for you huh.
Liara: Our travels differ slightly from my regular adventures. I'd like to spend more time exploring, and fewer explosions.
Liara: Yeah...every piece of technology I was going to take back to the fleet, has subsequently tried to kill me.
ALSO! I think the elevator rides are fine, considering there are next to no loading screens in games, the elevator rides, especially on the Citadel, are awesome.