That it's a shame that there are no cheats/weapons/costumes to unlock and use for a second playthrough.
Probably my biggest disappointment with this one. I really liked being able to 'mirror' the game for a second playthrough. There is literally no incentive to play through this game again. Not sure why they decided to omit these extras. It was fun, but when I got this, I also got Arkham City. When I was playing through UC3 I found myself saying "God I wish I could just grapple up there and glide" LOL.
The desert level with wandering was a pointless tech demo. It's almost like Naughty Dog was saying "look what we can do" for that portion.
The only WOW moment for me was the cruise ship level with the water effects. Epic!