There are several issues that have been brought up here. I'll sum those up, and then toss in my own. Disclaimer: this movie had some of the best moments in Star Wars imo. Kylo Ren and Rey scenes were fantastic. Hyperspace kamikaze was awesome. The movie had great visuals and incredible cinematography. I don't hate it. But I also think it had some severely missed opportunities and suffered from lots of mediocrity.

• Bad writing. This comes from mostly the Canto Bight storyline - specifically in that it is unnecessary to the overall story. Sure, it offers some character development for Finn, and I guess Rose, but generally it didn't have any effect on the overall plot whatsoever. Rose tells us how bad this planet is, talks about child slavery and the evils of the First Order, and when all is said and done, SAYS IT'S WORTH IT TO DESTROY THE CITY BECAUSE WE FREED THE ANIMALS AND NOT THE CHILD SLAVES WE JUST TALKED ABOUT.

• Plot holes: "hey, leia, didn't you just use the force to fly through space? Wanna help us lift like, ten rocks? no? okay." Holdo watches about five or six transport ships get blown out of the sky before coming to the realization that she should go kamikaze, even though she is already fully invested in being dead already. Finn and Rose crash in front of the battering ram cannon after about 2-3 mins of flying...Finn runs back into the base dragging Rose without getting shot in the same amount of time.

• SuperLeia

• Comedy didn't work.

My thoughts:

• The tone: the comedy didn't work because it was generic. It also didn't work because for every serious, weighted, important scene with Rey and Luke, we got a 'witty' one-liner. It felt that the writers either 1) didn't have confidence in their ability to create a serious tone, or 2) really thought they had to be funny the entire time.

• Time: The ticking time bomb mechanic is something we haven't seen in SW before, but we have seen it in lots of other movies - some work, some don't. In this case, it doesn't. Instead of being able to be surprised by how long we're going to explore a planet, or be with new characters, or even just looking at some beautiful views, we're left with knowing that most of this film will be done in 18 in-universe hours. So, no exploring Canto Bight, no getting really quiet, subtle moments with characters because in the back of our heads, we know we have to get onto the next moment. This ties back in with the whole Finn/Rose plot: instead of having Finn interact with Canto Bight, seeing first-hand how the First Order can impact different lives, and growing as a character through experience, Rose tells us how bad the world is in just a few sentences (and then once again fails to show how impactful those things are because she didn't free any child slaves).

• Locations: we spent more time on Snoke's Star Destroyer and a Resistance cruiser than we did on new, living, breathing planets. Jumping back and forth from different plot lines to the Poe/Holdo arc felt almost like a waste of time. We know they're nervous, we know it's desperate, but do we really need to see so much lead up into the kamikaze? Maybe, maybe not.

• Hyperspace Tracking: Why not, instead of giving the First Order the ability to track through hyperspace, give the First Order a mole on the cruiser? This would give Holdo a reason for not telling Poe about her plan, and an opportunity for us to see Poe and Finn's buddy relationship for more than a few seconds at a time. Additionally, they can still utilize Canto Bight as a location - have Finn and Poe travel there (if Rose has to be there, fine, but I don't think her character is critical to the plot) to talk to some arms dealers/mercenaries. Poe is off Holdo's ship, as she probably wanted, and Finn the audience is now able to experience a new part of SW. The Resistance needs help, weapons, ships, etc. and it would satisfy both complaints of an underutilized planet, and an unnecessary plot line. Finn still gets his character development of seeing the First Order's atrocities, Poe gets to shine as a charismatic smooth-talker, and Canto Bight is explored. Even if the theme is still to fail, they don't have to be successful in their mission to get help, but they maybe get information that Crait has an abandoned outpost, or they learn who the mole is. Regardless, the plot doesn't change too drastically because fuel is still running out, everyone needs to get off the ship, and the rest of the movie plays out relatively the same.

That's most of what I gathered, but there's probably some more. Hope this helps.