It is a mediocre movie in general, but as a Star Wars movie it is very bad.
As a movie it fails in a few places. First the jokes, oof. They are so out of place and each and every single one falls so flat. The jokes don't fit the theme, the characters, or the timing and are a distraction to everything the movie attempts to accomplish. It is way way way WAAAAAAAY too long. Particularly because how little happens to the characters and in the overall plot. Basically no one has any arc and everyone ends right back where they started the movie. So many subplots and characters could be removed and it would not change the story in the slightest. It is a mess storywise.
Beyond being a mediocre movie it really fails as a Star Wars movie.
It is clear there is a misunderstanding of the characters and they are butchered.
Poe was the one character that actually did have an arc, but that arc sucked. Poe learns to not think for himself and instead should always bow down to an authority figure, even when they appear to have nothing planned. So while this character development, its bad character development. There is no reason for Haldo to not tell Poe her plan. There is less of a reason why everyone on the ship, who also assumed that Haldo had no plan wouldn't join with Poe. I mean everyone is looking at their leader who is sitting there waiting for death, vs. ANY plan at all. Further, why can't the FO catch the Resistance? In a universe where FTL travel is the norm we have a tug boat chase? I understand it was designed for plot reasons, but it is so out of universe and jarringly stupid. The FO should just jump to light speed and show up in front of them, problem solved. If they really wanted this 'chase' scene, thye could have just fully stolen the BSG plot and had them follow with the Resistance only having X jumps remaining, same ultimate effect, but makes way more sense given the setting.
Chewie, poor Chewie. In the movie because he apparently has to be, but sits around and no one ever really acknowledges him. When he see Luke for the first time in a long time and tells him of that Han dies, he gets totally blown off. Chewie just lost the most important person in his life a mutual friend of his and Luke. Also Luke and Chewie are friends, they have gone one some pretty serious adventures and bonded, but here he shows up devastated and then immediately turned away and spends the rest of the movie hanging out with a (somehow) ***** version of the Ewoks.
Leia, the Mary Poppins scene.... Leia who has a passing ability in the force all of a sudden has a pretty amazing power to never killed. Which is also, 100% pointless. Beyond how utterly stupid the scene watches, and it watches very very poorly, why does it occur at all? Leia is seemingly killed to just to end up mostly fine. The only potential payoff (Kylo pulling or not pulling the trigger) is rendered totally inert, because, surprise, Leia is an unkillable Jedi Master of the highest order apparently.
Luke was so totally misunderstood, and it is the most infuriating as it harms the character deeply. Like Yoda, Luke, while also being brooding and a totally loner, is also working on his opening act at The Comedy Store. That makes all the scenes with him confusing as they jump from serious to awkward and back again. Then his entire character is tossed in the bin as nonchalantly as he tosses his old lightsaber. Luke spends all of RotJ believing he can reach his father, that there is still some good left in him. No one else in the galaxy believes that, including the Emperor. The payoff becomes that Vader does still have some good left in him and makes one last sacrifice to save his son, who had still believed in him. So THAT guy, the one that believed the most evil man in the galaxy still had some good left in him and could be saved, somehow looked at a child (who was not evil yet) and thought the ONLY option is to kill him. And it wasn't even a passing thought, like say Ben read his mind and saw he thought that, or Snoke planted that image in his mind or something reasonable. This was Luke showing up with lightsaber in hand only to back off at the last second. That is so bad so utterly misguided and out of place for Luke. It is no one Mark Hamill made comments like this character was not Luke Skywalker before the film was released, he was right it wasn't.
Yoda the wisest being in the Star Wars universe shows up to do his set at The Comedy Store. Blowing right past the, "where the fu*k have you been the last 30 years" and how are you able to impact the real world as a force ghost, the movie depicts Yoda as the goofy weird creature we see when Luke first meets him. However, that is NOT Yoda. Yoda is putting on that act to test Luke, to see if he is "ready", so for Yoda to come back acting like a goofy asshat, I mean how do you miss the character that much, at least you coulda listened to the Weird Al song about him and had a better idea about him.
Rose and Finn didn't need to be in this movie. They accomplish nothing but being filler in an already bloated movie. The entire fake Cloud City story is totally pointless to the story, but also really bad. They go to find the only guy in the galaxy that can accomplish the hack only to find someone else equally as capable, literally just lying around. They free a bunch of space horses from their space horse racing (hooray!) expect this is a pretty small planet or moon or whatever, so where the **** are they gonna go? They are clearly going to be caught, by the wealthiest people in the galaxy in like 30 mins. If they don't, did anyone check to see if they can even survive in the wild? And, best of all, glad they saved those CGI monsters, but the kids stuck in slavery? Yeah, they should be fine. Then Rose and Finn head to the FO to accomplish more of nothing. Their plan is bad and dumb and they are all saved by BB-8 who can apparently take on the entire ship alone (why not just send in a **** ton of BB droids, as they are apparently able to accomplish way more than any human can in this story). Finally as Finn is able to do SOMETHING for the story (also pay off this character who began as a selfish coward, he now has the ability to be selfless and brave) he is stopped by Rose. Who lets him know they don't sacrifice themselves just to save others. How does she do this? By sacrificing herself (I mean she crashes her ship into him and is almost/should be killed and made them sitting ducks to just be killed). Also not to mention that Holdo literally JUST DID THE SAME ******* THING. But everyone forgot that she sacrificed herself to save the Resistance because she was a throw-away character that no one had any attachment to since they did not develop her even remotely, and it isn't like they had a leader character that the audience cared about lying around (*cough Leia *cough). Then because Finn did not sacrifice himself to save everyone they will all die, expect nope Luke shows up and saves everyone, by sacrificing himself..... Also now Rose and Finn are in love with one another even though at no point (other than the brief amazement Rose has at Finn when they meet) had anything happened to show these two becoming remotely romantically interested in one another.
Rey and Kylo sit around, almost have a meaningful transition to ultimately not, and somehow both get more powerful all while decidedly not being trained by their respective masters. Clearly the biggest miss of the entire film is that these characters are almost interesting only to be turned into nothing. Kylo has shows signs of weakness towards the dark side and begins to connect with Rey and then at the end, "Haha nope I'm still all dark side, thanks for the memories!". While Rey has the exact same dumb story with the light side. Visions of her being tempted by the dark and being rejected by Luke to only find a connection with Kylo only when push comes to shove there is zero tension and she is fully engaged with the light side. Having one or both "fall" to the other side is interesting or even better for them both to embrace their "outcast" nature and forge their own path, no light side, no dark side, all interesting. Instead there are hints here and there that there is a conflict within each of them only for when the payoff moment comes they do not hesitate and end up right back where they started the movie. Neither bats an eye about having any growth, not even the hint of losing their path and are firmly back where they began even though nothing in the story would have suggested they had cemented their ideals. Also, even though Kylo has been nothing but inept as a Sith, which is commented on frequently by Snoke. He has somehow increased his prowess so much that he can pull the golden wool over his eyes in the most telegraphed death sequence in cinema history. While Rey, who knew nothing before meeting Luke and is consistently not trained by him, now has all of the force powers and is totally an elite Jedi that can lift every rock ever. Luke had to sacrifice for these things. He abandons his friends to go train and for it they are ambushed and Han is captured. He sacrifices his training to go aid his friends at the last minute and for it he loses his hand and mentor. While stronger he is still a very incomplete Jedi which shows in his final confrontation where is clearly weaker and shows signs of faltering, when he lets his rage slip for a moment fighting Vader. Neither Kylo nor Rey sacrifice anything and in the end they get what they want, have more power than ever before, and in the climatic moments with everything on the line never show one iota of wavering in their faith.
Again not a great movie in general, but as far as Star Wars movies go, it is really really bad. So much was done to subvert expectations, which is fine, but you can't just subvert expectations just to do it. You have to have something that makes sense, both within the boundaries of a story and the greater universe it is set in. This movie fails both at telling a interesting story and really fails at trying to tell an interesting Star Wars story.