Heartwarming Moments: All around. The series - which presents itself as the most honest, raw portrayal of the group yet - shows several instances of the members having to work around difficulties together, only reinforcing their image as True Companions.
Misaimed Fandom: Due to summaries and screenshots of the infamous scene of Jungkook almost fainting spreading on social media, some people (mostly certain Vocal Minorities in other Kpop fandoms) accused the episode and the series as a whole of being a pity-party for BTS while other Korean groups go through the same or worse. Which, well, wasn't the point: the series was directly aimed at fans (hence the Youtube Red/Youtube Premium release) and explicitly meant to show a raw, honest look at the behind the scenes of the tour, with the narrative being that Jungkook overestimated his physical capabilities.
Tainted by the Preview: Some controversy arose from the first reveals of the series (via summaries of episodes 1-4), which mentioned things like Jungkook almost fainting backstage and V and Jin fighting. Many fans worried that the series would be exploitative, sensationalistic and/or distasteful, centering on the members' pain and potentially creating drama. This died down considerably after the release of those episodes, which were rather understated and centered on the motivations and thoughts of those involved (such as Jungkook overexerting himself to show his best for fans in BTS' last concert in Chile) and the dynamic of the group when facing these difficulties.
The film provides YMMV examples of:
Awesome Music: The film features gorgeous orchestral renditions of "Sea" and "Spring Day".
Broken Base: While some aren't bothered by it, the decision to have an actor as a narrator (who still speaks on the first person plural, as if from the perspective of the group) has been questioned by some fans and critics, who find it feels less genuine than it would have if it had been done by actual BTS members - especially considering that their sincerity is among the qualities that has made the group popular in the first place. The narrations at the end by Suga and RM were much better received precisely because of this.
Continuity Lock-Out: While there are non-fans who have enjoyed it, the movie is very much made specifically for fans. That means that it makes no effort to introduce the members, and a lot of jokes and emotional moments require prior knowledge of the group and their history (including the Hidden Track from LOVE YOURSELF: Her, "Sea") to really work.
Jungkook dramatically performs Suga's "First Love", only to trip ungracefully near the end. In an amazing example of comedic timing, "Outro: WINGS" kicks in at that exact moment.
V manages to learn Jungkook's choreography for "Begin" very quickly.
J-Hope nailing the high note from "Stigma".
Some of the montages featuring performances set to the Awesome Music mentioned above can truly give chills.
One-Scene Wonder: According to reports from both news media and fans, the moment that universally got most screams at the theater was not a performance or anything focused mainly on the members, but the entrance of none other than Yeontan, V's dog.
They Wasted a Perfectly Good Plot: A criticism of the movie (one that has appeared in otherwise fully positive reviews) is that the actual concert or even the full performance of one single song isn't fully shownnote Even if the performance is shown, it's often only partially or with the original soundtrack playing over slow-motion shots., even though the movie appears to build up to it. Conversely, given the fact that this movie is aimed at fans who already have prior knowledge of their music and history, a full performance might have simply not been necessary.
