The answer to the question that most are asking, following the huge internet buzz that resulted from the release of critics ratings, is this: it is definitely far from being the worst MCU film, but as a MCU film, it’s not the most memorable one, even if, thanks to Zhao, visually and storyline-wise it is one of the most distinct Marvel films.
In an almost unprecedented fashion, Eternals is non-linear in its story structure, one of its many perks. The issue in the first 40 minutes of the movie is that the flashback scenes prove to be more interesting than the main storyline. It feels almost as if this parallel storyline could have been expanded in a more interesting full feature film. Eventually, threads are connected and the non-linear structure becomes interconnected enough to justify the unification of the subjects in one single film, but the “present day” storyline lacks coherence in some aspects. Without spoilers, in the end a character’s actions prove illogical to the sequence of events, another character exits the scene but afterwards acts as if it was present for the climax, a villainous character seems to have been forgotten for a good portion of the film and ends up horribly underdeveloped. None of these issues are new to Marvel films, but they definitely prevent Eternals from being counted as one of the better ones.
Ultimately, the biggest issue of Eternals is inherently linked to it being an MCU film. The Marvel signature approach, that demystifies superhero characters and turns them into comic figures, flawed and human, hardly works well for a set of god-like entities with millenary lifespan that have guided the early evolution of mankind, such as the Eternals. Truthfully, their humanisation leads to emotional developments, but also to a set of immature behaviours that are hardly justified on characters that hold millennias of wisdom. Some of the Eternals behave according to their physical appearances, even like teenagers. Paradoxically, a more dehumanised, mythological depiction would have most likely worked better, similar to how Snyder represented DC’s superheroes in Justice Leagues, almost as greek demigods.
In terms of MCU lore, Eternals brought forward a vast area of expansion, that if implemented well, might possibly lead to new directions for the franchise. Weighing the pros and cons, Eternals leans more towards the postive, but its flaws prevents it from utmost greatness.