I'm not sure what extensive knowledge of Greek mythology one needs to follow this simple story really.To be blunt basic knowledge of both Greek and Roman mythology should be part of anybody's education. Having said that there could have been a better prologue maybe to explain who Kronos was , and why was he imprisoned by his own sons.
I did find this a notch below of "Clash" mostly because it felt less epic, and the fight scenes just lacked any excitement , especially between Perseus, and Ares. Rosamund Pike was wasted on this, and Bill Nighy recycled some of his acting styles from Underworld. Surprisingly both Fiennes, and Neeson did better then expected based on the first film, I guess they got something to work with.Audio was a knock out for sure.