The movie is almost 1 hour and 19 minutes long so it's shorter than what I had expected. But recap movies like these are usually short so it's probably better that way. Almost 95% of it is recap though so that might be disappointing to some people. If you don't remember the plot of the main series then it's better to just watch the whole thing. It doesn't include everything from the original anime/manga so some of your favorite moments from the anime series might be missing here. But I think this anime does a good job with its pacing by including most of the important plotpoints (the last half of the movie is mostly the last episodes intact). Good pacing isn't something you normally expect from summary movies so I thought that was great.
If I'm not wrong, the last episode of the anime came out before its source manga ended with its last chapter. So some vital info in the manga got cut in the original anime. Despite this the original mangaka Kumeta Kouji loved the anime adaptation of his work and even recommended it over reading his manga. I haven't personally read the manga yet, but I can confirm there's new content in this movie albeit very little. The overall ending of the anime series is still the same. Despite this I think this movie is still worth watching. But if you're stingy with your schedule then you may start watching from around 1:03:30 timestamp as that's where most of the new content starts. There's some new but short scenes with Hime Gotou (cv: Rie Takahashi) at the beginning of the movie though and some new narration by her I think but they're negligible.
This compilation film is in no way a replacement for the original anime. Rather it's supplementary to it.
