SUPER smooth, like butter... No... Smoother, no problems yet, but when I get one i'll be sure to report it.
Edit 1: Noticed something strange, when letting Device go to sleep, it looked like the screen brightness went all the way up then to dark... Not sure if that's an ICS feature or just something that happens once.
Edit 2: Let it sleep a few more times, didn't happen again.
Phone: Google Nexus 4 16GB
Under the hood: Stock
Body Kit: Stock