Yeah, it's a big game.
But gamers this generation are used to large file sizes, right? It should be no surprise to learn that Batman: Arkham Knight requires 45GB of space on PlayStation 4, Xbox One and PC.
The number can be found on the PlayStation Store, Xbox Marketplace and Steam, so we have to assume it's correct. The good news is that the new systems make it a little easier to install and play games; first and foremost for me is the fact that installations don't take very long, and you can start playing before they're completely done. It makes uninstalling and re-installing games much less daunting as well.
That being said, lots of people still want Sony to announce a PS4 model with a bigger hard drive. And we just might see new version with a 1TB hard drive in the near future.
Related Game(s): Batman: Arkham Knight