Obviously, spoilers for the film, Hades Arc and other Saint Seiya material are to follow, so there's the warning.
The initial premise of Seiya left as an invalid, the Olympian Gods desiring control of the Earth out of fear of what Athena and her Saints have accomplished and Athena relinquishing control under the condition her sacrifice will stop the Gods from wiping out humanity are all good. That is where the positives for the first two acts end though as the rest is filled with questionable, contradictive or disappointing elements. The Gold Saints' souls being sealed in an unknown place not only isn't fleshed out, but seems an unnecessary punishment for destroying the Wailing Wall to prevent the Greatest Eclipse when it doesn't seem the Gods approved of Hades' ambitions. Seiya's condition is also utilised inconsistently with him quickly recovering from his coma and the claim that he can't use his Cosmo until after Athena's staff pierces him is contradicted by him being able to do anything to Icarus. Perhaps the most obvious poor element is the characterisation of Shaina and Jabu as abandoning Athena. Ichi is a little more understandable with his cowardly nature, but Shaina completely removing her feelings for Seiya as well as loyalty to Athena is character assassination that goes against all her actions in the series' 3 major arcs. The same can be said for Jabu when not only was he blindly loyal to Saori even before knowing her godly nature, but was willing to sacrifice himself to aid Seiya what was just days prior.
The battle against Artemis' Angels then begins, with it being a very rushed and lackluster experience. Not only are both defeated in very quick fashions with Theseus being oneshotted as soon as Shun and Ikki gain a resolve boost and seemingly gain the Cosmo of the Gold Saints and Odysseus is fatally wounded by Shiryu and Hyoga offscreen. Considering these two were capable of destroying Cloths even Hades' Judges couldn't, this is a very poor showing of such powerful characters. Icarus Toma is the only one who ends up mattering, with the reveal of him being Marin's brother being one good thing about the second act with that plot point being one that remained unresolved.
The third act is the best part of the film with Seiya's fight against Toma and Toma realising his flaws in a believable way. Athena only now using her staff to heal Seiya is questionable, though it can at least be assumed it was dangerous to do in his comatose state prior. The most famous and controversial part of the film is Apollo's appearance with him easily defeating Seiya and wiping the memories of him and Saori. This is fine for the idea of this being a prologue to the next arc and is the only real option given to the Gods beyond destroying them at that point, though it not being delivered on further obviously impacts its value.
One element the film succeeds at well are the superficial aspects. It has art and animation the franchise has only matched or bested through the previous theatrical releases (mainly due to the better colour tones within hand-drawn anime), the soundtrack has many iconic tracks of the anime and good new additions including a very good ending song and this is the last hurrah for the series' original cast for the Bronze Saints and Athena whose performances are far better than their successors. However, none of these can make up for a sloppily written plot.
Overall, as far as far later continuations of an anime franchise through a film, it at least isn't as much of a plot-hole riddled mess as something like Dragon Ball Z: Battle of Gods, but is still far from being a product on par with what came before. It's still probably marginally better than the other Saint Seiya films due to having some sense of consequence and delivery on unresolved plot points, but it's still a redundant product with the more refinement of its ideas in Saint Seiya: Next Dimension. Only really worth checking out if wanting an idea of what Next Dimension may have in store once the pacing improves or if wanting to see some individual clips for the art and sound.
