Gonna do some adding today.
Anyway, I played Arkham City on the 360 and Wii U at the same time, doing my own "Digital Foundry" type thingy. AC is installed on my 360's HDD, for the record. Anyhoo, there was definitely a noticeable improvement on the Wii U side of things. The game just looked sharper and less jaggy and items in the background looked more solid (like tables and windows). The Wii U had to stream from the disc and, as a result, there was a noticeable stutter when you zoomed over the city. Just wanted to post that somewhere since I was expecting the Wii U version to look worse--based on some reviews.