I feel like RoS was like a big bowl of candy. When I'm watching it in the theaters, just stuffing candy in my mouth, I enjoyed it.I agree. I actually really enjoyed Rise of Skywalker, to tell you the truth.
Then I left the theater and actually thought about what I had just watched (aka the sugar crash), and that's when I realized just how bad it was. And the sad part is, there are some interesting scenes. When Rey supposedly "kills" Chewbacca, man that was a shocker....and if they had actually let that play out in character (even if they bring chewy back in the end, give us some time to see how Rey reacts to it), that could have been really cool.
The Diad thing I thought was neat, and the switching weapons with each other was pretty cool. When people are saying "the force can't do that", I'm like "yeah that's the point, this diad thing is new, its unexplored territory". However, it was also an example of something someone thought of at the last minute as opposed to integrating it into the story. If Rey's phenomenal growth had been foreshadowed more, "maybe luke goes.....her power is immense but more than that, her knowledge and skill.....she can't be untrained"....something something, and then the Diad thing is a way to pay that off (she basically was "stealing" knowledge from Kylo) that could have explained Rey's power without looking like such a Mary Sue.
But as others have mentioned, the biggest issue in the movie is that it doesn't commit to the story that's been made. Love or Hate TLJ, its cannon, and you can't just ignore it exists. To bring up things in TLJ just to retcon them in RoS, its silly and stupid. Oh and also the dagger, that dagger is just the dumbest clue device in the history of clue devices.