The steel case edition was only sold in Austria by www.gamesonly.at. The game inside is the same as the regular edition.
The PlayStation 3 and Xbox 360 games both came in the same steel case. The PS3 case included an extra piece of foam as spacer, as PS3 cases are smaller. The back of the steel case is just blank metal.
2. Opened case with game
Thanks to unknown #1 (image 1) and unknown #2 (image 2).