I started new game plus and I'm quite pleased at how they didn't just make all your enemies hit harder! What they did instead was made it so you have to think more and since you already beat the game once you should know most of the tricks.
I have done all the Challenges from Riddler's Revenge now except three of the campaigns... But since I got the hardest ones done I figure it won't be too hard to mop the rest of them up.
I also finished all 440 Riddler trophies and Physical Challenges. I think I'm doing quite well.
I imagine one of the tougher trophies I'll have issues on is using all of Batman's combat moves in one flowing combo... I had a tough time in Arkham Asylum so I expect no less here either.