For me, the time travel mechanics are arguably similar to the first Terminator movie in the sense of past and future events being co-dependent on each other. So in that regard, I accept it.
The biggest issue for me is the Protagonist: He’s a blank slate of a character who only exists to serve the plot and that gives us no reason to care. He’s given no motivation whatsoever. Was that Nolan’s point, considering he’s only referred to as the Protagonist?