First things first: Remember all those awesome Hercules trailers? All those fantastic shots of The Rock fighting the Nemean Lion, the Erymanthian Boar, and the Hydra? If they were what had you thinking about seeing Hercules, don't bother. They are lies.
In fact, not only are they are lies told to potential audiences, they are lies in the movie itself. See, this Hercules isn't a demi-god, a son of Zeus, or even inhumanly strong — he's a regular guy whose impressive but totally mundane feats have sprouted a legend, constantly retold and embellished by his storytelling nephew Iolaus. So all those shots of Hercules performing his Labors and kicking mythological monster ass shown in every single trailer and TV spot? They are part of a montage, as a captured Iolaus tries to intimidate a group of pirates, that ends within the film's first four minutes. I'm not exaggerating: All the monster fight footage is shown at the very beginning, and then is never seen again.
Because while this is a film ostensibly about Hercules, it lacks the mythology, the monsters, the gods, the amazing feats — any of the details that make Hercules unique and interesting. Instead of being a demigod with incredible strength, Hercules is a regular dude, and Iolaus tells the tales in order to get mercenary work and frighten foes. Instead of a powerful, valiant warrior, he's a mercenary with a heart of gold who longs for a peaceful, quiet life, of course. Instead of battling ferocious monsters and fighting with gods, Hercules gets hired by the kindly lord of Thrace (John Hurt, whose half-assed performance is still better than most of the actors in this movie) to protect his hapless subjects from the evil Rhesus, who wants to conquer all the land.
And then the clichés begin. Hercules refuses to show anything that doesn't have a 3000-word TV Tropes page devoted to it; we begin with Herc training a misfit army of villagers into an elite fighting force as seen in countless films (there is literally a shot of Ian McShane teaching them to use a spear exactly like Ash does in Army of Darkness). Will the king force his unprepared troops to fight too early against Hercules' advice? Will the army get its collective ass kicked? Will Hercules give them a rousing speech and a training montage, and will they win their next battle? Of course. And then come the two tired "twists" of the film, which anyone reasonably aware of storytelling will see coming a mile a way. Hell, the movie doesn't even bother to lay the groundwork for them, because they're so insultingly obvious.
Here's the most infuriating thing about this movie: Brett Ratner clearly knows that people want to see Hercules do awesome things, which is why all the trailers consist almost exclusively of the (very, very little) footage of him fighting lions and hydra and boars, oh my. And yet Ratner has chosen to give us a movie practically devoid of what we clearly want. Why? Why would someone do this?
I believe that Brett Ratner is an Entertainment Vampire. By this I mean he finds entertaining concepts and sucks the entertainment right out of them. He did it with the X-Men — the X-Men! — by making the third movie a shittier rehash of the first two; and now he's done it with the son of Zeus, by taking away everything cool and fun about the character and turning him into a pretty strong guy who didn't know his dad.
Whatever charms Hercules has rest on the broad shoulders of Dwayne Johnson, whose old-school movie charisma makes the movie bearable — well, him and Ian McShane, playing a charming, fatalistic seer who knows when he's going to die. The rest of Hercules' posse exists solely to fulfill requite story beats and completely obvious arcs; one of them is Atalanta, whom the mythological Hercules never palled around with.
But the movie is so lazy that bitching about its utter lack of regard for Greek mythology, or the anachronisms, or the Greco-roman design confusion, is useless. Complaining would require you to care more about the movie than Ratner ever did, so why bother?
Let me give you one such instance. Hercules and his still-poorly trained army are fighting a bunch of evil bald yellow savages with goatees. The battle is pretty much chaos, with Thracian soldiers fighting these rejects from 300 all over the place. At one point, Ian McShane bursts into the battle on his chariot — out of which giant blades shoot out of the sides to cut down foes because… who cares? Now, anyone with any sense of spatial reasoning would see the trouble here, but of course in the movie McShane's chariot somehow cuts solely through evil bald yellow men. Why worry abut trying to figure out who he'd really be cutting through? Why confuse people with the moral complexity of a hero harming friend and foe alike? Why even bother to have McShane actually hack at people himself when we can have a chariot with senseless fold-out blades on it? Why put in the effort of doing something difficult, or trying something new?
The movie doesn't care. It doesn't care about Hercules, it doesn't care about telling a story you haven't heard a thousand times before, it doesn't care to show you anything you haven't seen a thousand times before. And it certainly doesn't care about you enjoying it. Do yourself a favor, and don't.