Rogue One: A Star Wars Story has been met with overwhelming praise, giving Star Wars fans the prequel they always deserved and making more at the box office than anybody expected of a Expanded Universe-hued spinoff. There are a lot of great moments, too many to list here, but it's fair to say based on how his name has been trending as much as the film's title that the real highlight is Darth Vader.
Righting the somewhat wobbly characterization of the prequels and returning the Dark Lord to his menacing former glory, it was a short but oh-so-sweet few minutes of screen time that tied perfectly into his A New Hope entrance with just the right amount of elaboration. The first scene, around the mid-point, revealed a lava castle ripped straight out of original trilogy concept art that transformed Vader into almost mythological figure in the Imperial ranks, while the second is the most exciting use of the Force in the entire franchise bar none. It's so perfect that many fans are now pushing for a whole new standalone just for him.
Still, almost fitting of something as obsessively dissected as Star Wars, there is inevitably one part that’s still contentious: the pun. At the end of Vader's first scene, Director Krennic asks him if he can circumvent Tarkin's grip on the Death Star, but finds his breath cut off and falls to the floor as Vader turns around to reveal his Force grip, remarking, “Be careful not to choke on your aspirations, Director.”
For some that was simply taken as a moment of Vader’s ultimate confidence: humorous, yes, but ultimately showing the power he wields (and making Krennic’s situation that more precarious). For others, however, the line fell flat, with some arguing that a terrifying figure like Darth Vader shouldn't be having fun with puns.
Upon first inspection, the dislike of the line seems fair. Darth Vader, a Dark Lord of the Sith who all but destroyed the Jedi Order and struck fear into the entire galaxy, was cracking wise and enjoying some yuks mere days before the events of A New Hope? It’s not quite as damaging as Hayden Christensen’s wooden acting, but at least his sand monologue was buffered by Anakin being pre-transformation. This is supposed to be Vader at the height of his power, yet the line makes him not much better than a Marvel villain - quipping lest the film get too dark. There have even been comparisons to Jar Jar Binks.
But, really, is it all that out of character for Vader? It may be easy to rage at the tragic and terrifying Dark Lord of the Sith having fun, but the original trilogy is absolutely littered with examples of him making colorful statements at others' expense to often darkly comic effect: “Apology accepted, Captain Needa” after choking an apologizing Imperial to death; asking Captain Antilles, “where is the Ambassador?” before snapping his neck and throwing him against a wall; condescendingly calling the Death Star a “technological terror.” In fact, when we're first introduced to the Force choke ability it's with Vader's wryly understated, "I find your lack of faith disturbing." It's not wordplay, but he is mocking Admiral Motti's arrogance as much as he does Krennic's in Rogue One.
To find the pun objectionable makes the assumption that Vader was simply a black-hearted menace in the original trilogy, which is far too simple. Threatening, sure, but he endured and was able to evolve in the sequels thanks to his underlying personality and, after Return of the Jedi (although it was hinted at right from the character's introduction with his incessant raspy breathing), hidden humanity. Core to this was Darth Vader's sharp tongue, which showed someone powerful, but acutely aware of the large shadow he posed.
When you break down the purpose of the statement with this in mind it becomes even less objectionable; having James Earl Jones say it puts the onus on Vader's gloating, but it’s really a targeted jab at the victim. Krennic has woken Vader from his bacta slumber to report that he’s failing at his mission and bickering with the Imperial high command in an attempt to curry favour with the Sith (and, in turn, the Emperor). Vader is above such pettiness and sees right through Krennic’s desperate bid, so tries to set him right using the most suitable weapon at his disposal: humiliation. And it works - Krennic takes the initiative, goes to Scarif and tries to correct his error. That he doesn’t succeed is besides the point - that’s due to factors outside his control - and a key part of Vader’s anger near the end.
Though it's understandable that some fans might not have liked the delivery of the line or its use within the scene, to call it out of character is to ignore the context of the other movies. Yes, the reading isn’t necessarily helped by having the turning reveal of Vader's clasped fist edited to make the choking feel like a punchline, but on a basic level it's totally fitting of the character and plays into an essential part of Vader’s arc.