I've heard that Mark Hamill doesn't like the way that Luke Skywalker was shown in the movie.
What is his attitude toward "The Last Jedi" and the development of his character?
Hamill's response to whether his vision for the character agreed with Johnson's was a stern
Hamill later went on to elaborate on his answer.
Well, I think when I read it, it’s like the movie is just mind-bogglingly complex. It’s challenging. It’s hilarious in parts. It’s suspenseful. It’s dark and somber. I’m holding the fort down on the dark and somber. But, you know, I mean, the most shocking thing I read was it’s time for the Jedi to end. Are you… What? And I mean, I understood Luke’s regret at being wrong about who the chosen one was and he feels responsible for creating potentially the next Darth Vader and hey, I mean, ruining your nephew’s life. Like not perceiving that he was going to the Dark Side until too late, so that weighs heavily on him. But all the characters face challenges in the second act of a three-act play or opera. I mean this is where all the darkest things happened. I mean, there’s triumphs of course but more than its share of tragedies.
Rian Johnson & Mark Hamill’s Vision For Luke Skywalker Differed Greatly - ScreenRant
As for the famous quote that's been going around the internet that Hamill "fundamentally disagreed" with Johnson's vision of the character, Hamill later went on to say it was poorly worded.
I was quoted as saying to Rian that I fundamentally disagree with everything you decided about Luke, and it was inartfully phrased. What I was, was surprised at how he saw Luke. And it took me a while to get around to his way of thinking, but once I was there it was a thrilling experience. I hope it will be for the audience too.
What Mark Hamill Really Meant When He Criticized Luke Skywalker's Direction - CinemaBlend
Mark Hamill also expresses his excitement for the film's release and hopes the public will enjoy it as much as he did.
Rian Johnson is an amazing filmmaker. And if you look at Brick, or Brothers Bloom, or Looper, each film is different from the last one and they're so inventive. And I think people will be really pleased and surprised, I know I was.