Kyoukai no Kanata: I'll Be Here - Kako hen is the first part of the movie series. This part is a complete recap of the original anime series. It does a good job getting you up to speed as to what happened in the original series and is only dedicated to the events surrounding Kanbara Akihito and Kuriyama Mirai and doesn't indulge in side stories.
This is a really good summary of the original series. No new scenes are used. It reuses the scenes from the original anime to make this summary.
The story of Kanbara Akihito and Kuriyama Mirai is explained. It does not go into the side stories like with the Nase Family, Inami Sakura and Fujima Miroku.
Since it uses the same scenes, it has no change in art. It's the same KyoAni which you've already seen. The artwork is amazing. Nothing more to say.
Both the opening and the ending are really good songs. They are played near the end of the series.
The opening is played when Kanbara Akihito reaches Kuriyama Mirai when she is fighting Kyoukai no Kanata near the end of the movie.
The ending is played at the end and is a full version. It is played through the credits.
Voice actors are same.
If you haven't seen the original anime and watch this movie only, you'll miss out on many characters. As I said before, this movie focuses on Akihito and Mirai so the other characters get very little to no screen time. The only side character to have some play in this movie is Izumi Nase.
I loved the original anime and I liked watching the summary too. Even though it is a summary, some comedy bits are placed in it. And there are some emotional rides too.
It's a really good summary and for fans of the series, it is a good way to catch up and remember what happened.
Overall, I liked it. A heads-up, in the end of the movie, after the credits, they give a preview of the next part of the movie.