Right, firstly this is not the classic Harryhausen from 1981, the plot and story have been changed, I would need to go off and do some research to see which is the most faithful to the underlying mythology.
This is not an epic retelling which will replace the stop-motion version in the hearts of geeks everywhere, though the CG animation is very good and just continues to show what is possible with a pile of artists and some seriously powerful hardware. The pegasus was partiularly impressive.
It’s a quest movie, go here, do that, kill this, chop the head off that, loose most of the redshirts along the way, loose some companions, get them back at a critical moment, heroic sacrifice and so on. Though it didn’t feel like the lead had the drive to go and do stuff, he went along because the story was telling him to do so but without any “I’m doing this for …” or “I’m doing this to prove … wrong!!” just “feh, I’ll go along and kill things and use the plot devices at the right moment”.
So, see the movie, put your brain on a peg for a while next to your disbelief and enjoy the ride and then go back and enjoy the original.