It's interesting to see some people putting the critical acclaim in perspective. While few doubt that the game deserves considerable praise, these same people are questioning the way the shooting and/or violence is seemingly at odds with the narrative and setting.
The recurring them is that the game itself raises an important question about the nature of gameplay, and people have been wondering if the environment and story could have been put to much better use. To cut a long story short: why is Bioshock Infinite a first person shooter in the first place?
The only parts of the game that were any more violent than what you would expect from an FPS is how Booker executes people with the sky-hook. Seriously, the first guy you kill in Columbia was a lot more violent than I was expecting, shoving some guy's face into a rotating blade, basically.
To cut a long story short: why is Bioshock Infinite a first person shooter in the first place?
It's a triumph of the medium that I can use lightning bolts to pop a constable's head like a zit and use my rotating hook-blade hand to mutilate a hapless bystander while simultaneously being treated to an unprecedented blending of social commentary and quantum mechanics all under the guise of a highly personal story.
Oh, and Kotaku is consistently awful, by the way—saying the violence in BioShock Infinite limits its audience is not only just as much of an understatement as claiming "Django Unchained's violence limits its audience," but equally misguided. Tsk, tsk.
"An Incandescent Revelation in a World of Darkened Forms" The bird of Hermes is my name, eating my wings to make me tame
The major theme, or even any of the minor themes, have nothing to do with gameplay or games themselves.
Maybe gaming would be taken seriously as a possible art-form if not for the mass of plebeian gamers that can't possibly pick up on any themes other than those that directly relate to their biggest hobby.