Imaculata
Hero
If you feel it (Vader scene in Rogue One) was pandering to fans with special effects eye candy, then you must think less for everything else in the movie loaded with fan pandering and eye candy effects. But the fact is that the sequence stands out, not for what it presents (Vader being a total badass) but how it is presented (through the eyes of the common Rebel soldier).
I DID think less of almost everything else in Rogue One. Its poor screenplay, its poorly written characters, and the fact that I didn't care at all about what was at stake, because of said poor character writing. The final battle looked amazing, but ultimately if you don't care about the characters or the plot, then it falls completely flat. Rogue One was not a Star Wars film, it was a Star Wars fan-film. I understand that a fan-film filled with fan service can still be appealing, and I don't think fan service is bad by default. But this movie had no other leg to stand on, and some of the fan service even undermined the movie itself.
The scene with Darth Vader at the end was a perfect example of the film makers thinking Vader is cool, but not really grasping what makes him work in the classic films. It's not about showing his actual force powers, it's about a looming sense of dread. They could have simply let us hear the screams from behind the door and cut away right there, without showing any of it. But they couldn't leave it alone.
What they really should have done in my opinion, is end the movie with Jynn on the beach. That would have also avoided the creepy CGI Leia. It also would have helped if they showed Jynn being a resourceful tough lady, instead of telling us that she is (The old show don't tell). Additionally they could have given some of the jokes to any of the other characters besides the droid, so they would be remotely likable.