I like the laser beams which are 25feet long and rotate 360deg in nightmare which arent in normal. And my friends say they hurt in hell so much that you die if you stay longer than 1sec in it.
Also the bees in act2 which spit poison now root you so that you have to use cooldowns in higher difficulties, or you will die very quick.
And there are many other small changes and abilities which makes it more interesting.
And enrage timer on inferno too :)







