It sucked.
Liam Neeson (Zeus) looked bored. So did Ralph Fiennes (Hades), probably because the two normally great actors were hidden, even as gods, behind stage makeup and fly wires that were better used on the marionettes in The Sound of Music. Sam Worthington was Perseus. He looked mildly constipated.
The story follows Perseus, whose father, Zeus, falls for a human woman who is married to some non-god, so no problem there.
Anyway, Perseus the half-god must kill Poseidon's pet Kraken, because otherwise it will eat his girlfriend in order to spare her home town. He could use his godly powers, but he hates his father, the creator of everything, and doesn't want to be like him. (I'll give him that. It's a lot to live up to.)
Some soldiers go with him so that the movie doesn't have to kill the hero. They visit three blind witches who share an eye the size of a softball and like the taste of people.
The witches tell him to find the Ferryman, cross the river Styx to the Underworld, and bring back the head of Medusa, a woman-snake hybrid who can turn anyone, including the Kraken, into stone with just a glance.
At this point I'm sure you want to see this as much as I did, but the real jaw-dropper is how they managed to make a great story like this so boring.
A cgi effect played the Ferryman. He took the actors across the river Styx and into Hades, a journey so bland that I felt like I was repeating my stroll through the theater's parking lot.
A pretty good cgi effect starred as the Kraken, hopefully worth all the money they spent giving him one minute of screen time.
There were also giant scorpions. They were awesome.
Whoever played Medusa had a fun, wicked laugh, but she was upstaged by her snake half, and when I saw her gaze I thought, hey, a computer did that. (As an armchair filmmaker, I think that gaze of hers would be much scarier if she did it with her back to us. That applies to the original film as well.)
The action scenes were good, they made me dig for the popcorn. But, like vacations, they were few and far between, with much labor from one to the next.
All the other gods looked like chess pieces hanging out in the lobby of Mount Olympus.
This movie was nothing more than an exercise in special-effects showboating, designed to blow your mind without actually expanding it.