[Spoilers for the movie and anime series(pls go watch the series it's really good unlike this movie)]
Ill start of by saying I haven't played the visual novel,
But you don't need to have played the VN to see what the problem is with this movie, It's a recap. And there is simply too much to put into a relative small time frame for a movie.
Characters are being shown like cameos in their own story, characters have no motivations, nothing lead up to the ending, for what reason is Tomoya emotional at the ending? etc. etc.
"For what reason is Tomoya emotional at the ending?" is a good question especially because, remember how long it took Tomoya and Ushio to accept and understand each other in the anime?. The two seconds it took for Ushio to see Tomoya as her father is baffling. And in my opinion shows perfectly why the movie tried to do too much in too little time.
And if Tomoya has no reason to be emotional, why should we be emotional with him?