Compared to Fate Stay Night, fate Zero is a much more darker and more adult story which to be honest if you've seen Fate Stay Night you know how it ends.
The historical research for the servants is impressive by using some quite obscure historical figures and then fitting their Master's story around it, the best being Lancer.
Despite its pluses the story takes time to get going by introducing the Masters and explaining their reasons for taking part in the Grail war which include ambition, to save a loved one, getting respect, warped sense of justice and simple murder which became a bit boring and humourless saved only by the relationship of Rider and Waver and finally the fight between Lancer and Saber.
Best way to describe this is too much story and not enough action.
