Some random thoughts about The Last Jedi...
The characters never change. One of the main aspects of any story is that the characters develop. The sum of a character needs to be more at the end of the film than at the beginning. After all, the point of any story is to tell...well...a story that is interesting and has value. Rey, Finn, and Leia are the same at the end of the film as they are at the beginning. Leia is a supporting character in this film, so her remaining unchanged is not too awful. However, Rey and Finn are two of the main characters of this new trilogy. These characters should've changed in an interesting way, but they don't.
There was an opportunity to have Rey undergo at least one major trial on her path to a Jedi. In the scene where she is pulled by the Dark side in front of Luke, Luke mentions that she never bothered to resist. Assuming he is right and she didn't resist, the draw of the Dark side had no lasting effect on Rey. She shrugged it off as if it never occurred. She later succumbs to that pull and seeks out the cave, but nothing interesting happens. What started out as the focus of the Dark side on the island turns into nothing scary or even remotely powerful, let alone meaningful. The Dark side was rendered as ineffectual as a speed bump.
I do think Poe and Luke changed a little in the film. At least Poe became more of a leader and less of a brash pilot by the credits. Luke even learned to accept his place in the universe. Both of these characters should've developed more before the end of the film; had they been given that opportunity their changes would've been more pronounced. As it stands, their change was minor.
This brings me to Finn.
Finn's story is completely pointless. If you cut out Finn's entire story arc, nothing in the film changes. At. All. If anything, Poe should've gone with Finn to Monte Carlo. At least the two could've developed a stronger bromance and their relationship as friends would be believable. It would've been an opportunity to have some great speeder chases with them trying to outrun the local police. There is little reason why these characters are, or should be, friends, but spending screen time together could have developed that friendship in the eyes of viewers.
General Purple is not a leader. People may carry titles like commander or general but this is a far cry from a disciplined military force. With morale running low (they were being obliterated by the First Order's fleet hot on their tail), General Purple needed to raise the spirits of the crew and give them reason to fight. She should've taken a page out of Admiral Adama's book about fleets-on-the-run and briefed the crew on her plan, which was to get to a secured and hidden (albeit abandoned) base. Doing so would've kept Poe from committing a coup and he could've started becoming the leader the resistance needs him to be.
Leia should've died in space. The moment Leia is sucked into the emptiness of space was an emotional high point in the film (or low point depending on your point of view). I couldn't help but think of Carrie Fisher's death. The emotional impact of seeing Leia die on screen was a parallel of Fisher's real world death. The scene carried a lot of weight, and it was quickly undone when she zoomed through space looking like Mary Poppins.
Poe does nothing in Act 2. He runs around like a crazy person, but does nothing of any substance or value. Act 2 was an opportunity for more space battles. X-wings could've flown missions to save crews on other fleeing ships, for example. It would've given the audience some "wow" moments that could've revved up the fleet chase and made it less boring.
Awkward and misplaced humor. I admit, there were a few moments where I laughed out loud. The rock crushing the cart was a great moment. Every moment with BB-8 was adorable and filled with joy. The beginning sequence between Poe and Hux, and Rey reaching out were just awkward. The moments with Rey and Luke could've shed more light on the Force. There's so much about the Force, and about Jedi, that we don't know, and more seriousness about that "hokie religion" would've been a great addition to the mythology.
Rey, as the hero, overcomes nothing. Look at every great hero story and the hero must overcome great odds to transform into something greater. Rey doesn't transform into anything. There's no challenge for her. She couldn't even overcome Snoke, she didn't even try. She didn't battle some inner demon. She didn't fight against the Dark side. She hung out with Luke then she left to save the day, from what, exactly, we don't know.
The film erases interesting elements setup in The Force Awakens (TFA). Snoke was built up to be a menace. He dies with the audience learning nothing about who he was, where he came from, what his motivations were, etc. Now granted, the way he dies is great. The entire death of Snoke and the battle that followed was the best thing in the entire film. It may be the best thing to ever happen in the Star Wars movie-verse. Also erased were The Knights of Ren, Rey's background, and why Luke went into hiding.
By the end of the film nothing has changed. The heroes are at the exact same point they were at the beginning of the film (although Finn is conscious--but he should've been dead, but whatever).
The only interesting character in this series is Kylo Ren, Ben Solo. Once again, the moment he kills Snoke is amazing. The moment you realize he's on Rey's side was absolutely thrilling. We haven't seen something like that in the series. Sure, we saw something close when Vader turned from the Dark side, but he immediately died. We had an opportunity to see Kylo Ren go good and struggle with that decision into the next film. Instead, Kylo Ren becomes the new supreme leader and the emotional impact of his transformation is rendered moot. He's still, however, the best thing going for this franchise.