Like where I do even start with the changes they made to the story. A minor one is changing the ghost girl that Ichigo makes the thugs apologize too into a boy. A major one they did was go with the idea that Ichigo can transfer his Soul Reaper powers back to Rukia if his Spiritual Pressure is strong enough. If it's not, he'll probably die. So she trains him and makes him fight the hollows in her place until it gets high enough. They made Byakuya and Renji appear much sooner and not just take Rukia with them at once. They give them until the next full moon to take her powers back and kill Grand Fisher, or they'll kill her and Ichigo.
The movie expanded and changed Grand Fisher's role a lot. They made it so it was waiting for years for a chance to get Ichigo again, when in the manga/anime it's preferred victims are young children and it didn’t know who he was until later. They gave it the power to make illusions. Instead of having him stab Ichigo to find out what he can't cut and change his lure to his mother, he made Ichigo see her back on that road. And the fight in the manga/anime was in a isolated area, the fight between him, Ichigo and Uryu, (he appears early too with the hollow bait), together in the movie spills out into the city. I liked they how showed all the stuff being destroyed by this seemingly invisible force like at the start of the movie, but it reality, it's these ghosts fighting each other.
And they actually managed to destroy Grand Fisher, when he barely got away in the anime/manga.
And finally, Byakuya and Renji show up again after they destroy Grand Fisher and the fight between Renji and Ichigo was actually pretty good. I liked how they showed powerful Byakuya was too. The last thing he does before putting cutting Ichigo for the last time was when Ichigo went for a slash, he simply stopped it with the tip of his sword, knocked it down, and quickly cut him down, already sheathing his Zanpakuto. Oh, and Rukia actually took her powers back from Ichigo and went back to the Soul Society with them. Also, they erased and changed everyone's memories of the incident. At the end of the movie, Ichigo sees the message that Rukia left him in the textbook.
I don't know how to feel about what they did with the Quincy Bangle Uryu has or his bow. They made it so that he takes off his wrist, pulls one with a string, and forms the bow that looks more like the one formed using the Sanrei Glove. The one in the arc that they're adapting was just one made up of Spirit Energy. The one shot of the Soul Society and the Seireitei was amazing though, it looked just like it. I liked how the Zanpakuto and the Hollows along with the way Zabimaru looked too.
Tatsuki, Orihime, Chad, Urahara, Keigo, and Ichigo’s family were in the movie too, but besides his family, they didn’t appear that much. But I think the movie got everyone’s character right, so it had that going for it. So yeah, at best, it’s an okay mess, and I still would have preferred a 5th animated movie. It was better than I expected of an live-action anime movie.