Blue Lock: Episode Nagi

To begin with, this movie could also be called "Episode Reo" because his character is developed just as much. We get to see how he meets Nagi and their progress in Blue Lock, but this time from their perspective.

Positive Points:

A first part without football. Some might not like it, but I found it refreshing to see character development outside of football. It makes them feel more human, and we get to appreciate them more.
Reo's development. If you don't watch this movie, this player will probably remain forgettable for you, as he doesn't get much spotlight in the ... main series. But here, we see him from a different angle, and he actually became my favorite character thanks to this film.
The relationship between Reo and Nagi. We learn to appreciate the bond between these two and understand much better why Reo felt betrayed when Nagi left him in Blue Lock.
The OST.
The animation is on point.

Negative Points:

The Blue Lock part isn't interesting. Some might enjoy it since it features matches we hadn't seen before, but for me, it was forgettable. I'd rather rewatch those moments from Isagi's point of view.

Conclusion:
You'll likely enjoy the first part, which focuses on the meeting between the two protagonists. You can skip the second part if you're not particularly a fan of Reo or Nagi.

For anime´s only you´ll probably enjoy this movie as it works as both a recap and you get to see more of Reo and Nagi´s (borderline homoerotic) relationship, including its origin.

However having read Episode Nagi´s manga, this movie feels like a wasted opportunity, as it only covers the first 24 episodes of the anime. Meaning it´s going straight to the U-20 match, missing both exciting matches along the way and crucial development from certain characters (especially Nagi and Barou).

Moreover, the animation feels lackluster and the art style does not improve much from the anime.

In conclusion, while decent, the movie works more as a recap ... than a stand alone product. It´s still enjoyable though.

I do not recommend this movie in its current form. As a spin-off, it had the potential to build on an already strong foundation, but instead, it falls short in almost every aspect. The story, which could have been compelling thanks to the manga’s richness, ends up feeling more like a recap, with about 80% of the film consisting of reused footage from Season 1, and only a few poorly integrated new scenes. Important plot elements and exciting moments from the manga are either glossed over or completely skipped, resulting in a loss of emotional depth and narrative impact. The art and animation are equally ... disappointing—no effort was made to improve the sloppy animation or outdated CGI from the series, which feels especially underwhelming for a theatrical release. The characters come off as flat and underdeveloped, with little room for realistic growth or reactions due to the rushed pacing and heavy reliance on old content. While some die-hard fans might appreciate a few of the new scenes, most viewers—especially those familiar with the manga—will likely feel shortchanged. Instead of expanding the universe in a meaningful way, this movie feels like a missed opportunity and a mere cash-grab that adds nothing new or worthwhile to the franchise.