360 & PS3 demos are identical graphically, however I did prefer the 360's controller. The triggers felt better suited and as most of the action is grafted onto the triggers - that could make quite a bit of difference to a 12-20 hour game.
Definitely a purchase regardless, just can't decide what platform to buy it on.
Oh and I don't think I've played a 'demo' of any game as many times as I have this now.
I have found the answer to my problems!!

Cheap little attachments I ordered off of Amazon could solve this whole conflict on controllers. Yes, I love the Xbox controller but i have a PS3, so i bought these. Cheap!