It has come to light in the last couple days that the PC release of this game was horribly, HORRIBLY bungled, to say the least. So badly that Valve has temporarily suspended sales of it on Steam - I imagine at least in part because of people demanding refunds, something Valve recently introduced to the platform.
http://store.steampowered.com/app/208650/Reviews provide further details, but the game is experiencing awful performance issues. Now, it seems reasonable to expect that a PC version of a game maximize performance potential. But apparently, Arkham Knight's PC version has a framerate capped at 30 FPS but often can't even maintain that with stutters and some users reporting framerate drops into the single digits, at which point you're basically playing a slide show. Texture resolution is lower than the console version. It is also horribly buggy and glitchy, to the point of unplayability for many users, and has memory leaks leading to system crashes.
It seems that the team responsible for porting this to PC was an outsourced studio made of 12 people...which is not enough people for a big name release like this unless they have a LOT of time to tweak that 1% of a game that needs changed for computers. It was supposed to run on Windows, Mac and Linux but effectively runs on nothing. Rumors are circulating that this 12-person team had less than 3 months to port it to PC..which is nowhere near enough time. The NVIDIA GeForce Experience can't even optimize the game's graphical settings, despite it having the NVIDIA "The way its meant to be played" logo when started.
Something, someone, somewhere, really messed up with this, and the reviews on Steam (mostly negative due to performance issues) more than show it. I'm sure the game itself is quite good considering the precedent of the other Arkham games and the console version has been getting great reviews, but when it's crashing, glitching, and just not running the way it should on a decent gaming PC there's a problem. It appears that PC gamers have been a bit alienated with this botched, big name release.