I could go on a big spiel, but I won't ... so here's the highlights
1. They waste the main villain, all the build up gone 2. They waste Luke, all the build up gone 3. Almost half an hour is wasted on Luke being a doink explaining all the different points of view about Kylo 4. The moral learned on the pleasure planet is wasted and immediately subverted 5. I don't think Rey and Finn even interact once in the movie... 6. They waste the secondary villain, all the build up gone 7. THE ENTIRE C-PLOT ABOUT THE MAIN REBEL SHIP 8. The First Order as a whole, except for one scene, wasted
Basically the whole movie is "how can we waste everything we set up"
Don't forget about Space Mary Poppins. They could have had that be the end, but they had her live instead and now have to write around her character being absent next film. ---