Berserk is based on the manga with the same name, which is about The Black Swordsman named Guts.
The series starts from the end with Guts hunting Griffith and his minions, then after the end of the first episode the remainder of the series is what I could best describe as the beginning of the series which shows the viewer how Guts and Griffith met, became enemies and also the love triangle between them and Caska.
Guts is on a quest for revenge under the name of, "The Black Swordsman," against a man named Griffith, who was once his very best friend and the former commander of the mercenary company, The Band of the Hawk. Then after the end of the first episode the remainder of the series is what I could best describe as the beginning of the series which shows the viewer how Guts and Griffith met as enemies of opposing sides, became friends through fighting, how Guts becomes the commander of the Raiders under Griffith and how they became enemies again fueled by the love triangle between them and Caska (don't want to spoil the other factor).
The three main characters of the story are Guts, Griffith, and Caska. Guts seems to be a character that is driven by the need to survive in order to be able to find his purpose in the world and the only way for him to truly feel at peace is to be in the midest of battle on a battlefield fighting for his life in order to achieve it. Griffith on the other hand is a man who see himself as a king even if he has common blood, who is willing to pave the road to his kingdom with the bodies of men who are willing to die for his cause (even Guts is no exception to this ideal) and selling his soul to demons in order to become king. Caska is the heroine of the story who is deeply devoted to Griffith, but is torn between following Griffith or falling in love with Guts and live a life that doesn't include Griffith.
The plot seems like a normal knight series like Lodoss War with sword fighting and battles, but then the plot takes a 360 in the last 3 episodes into a hellraiser like theme where all hope for survival is gone and only death by being devoured by demons remains.
The reason why I rated this series as average was because we don't find out how Guts and Caska survive, and that the last episode ends in hell and Guts all of a sudden is inside a blacksmiths shop.
It has a superb storyline which will make the viewer want to watch but at the end it just leaves the viewer with more questions then answers and a yearning to see more.
I would recommend this to anyone who liked watching Lodoss War and the Character Olsen. Guts is just like Olsen except that he is not under any demon control.
Good Luck and Enjoy!
P.S.: Just to let you know, the rest of the story continues in the manga.
Official Website: http://www.younganimal.com/berserk/