This anime is considered by many fans as the best anime of 2006; while it is a good anime its popularity is often over hyped and most ignored the major flaws of the series that kept it from being a masterpiece.
The basic plot is about Shirou; a high School boy with a very righteous kind heart but has a weak character and knows little magic. By fate he falls into an epic battle over the holy grail taking on the powerful Hero Summon "Saber" as his servant. The Servants do battle with one another till only one is left then taking the Holy grail to make a wish, but this battle devastates Shirou's life and opens up the secrets to traumatic events that happened in his past. The plot primarily is action/shounen/Drama... They attempt some Romance as well~ but its a little awkward.
Story: The story is one of the main flaws of this series; it becomes clear very early that this anime is based off of a "Visual Novel" due to its linear plot~ the goal is known right away and the development is predictable. There are some shocking moments towards the end, but that doesn't make up for the rest.
Perhaps the most stifling thing about the story is it hints about Saber's and other's pasts... but in never divulged any information. While sometimes its excusable to keep a mysterious story, in the case of this anime it felt vital to the plot, and rather than add to the mood of urgency it felt more like they were trying to rush parts of the series far too much... much of the events make no sense unless you play the visual novels or look up the background info online.
On the good side the plot is fast enough to enjoy after the first few episodes, Has alot of interesting battles and antagonists, and has an interesting back story if you watch untill the end.
Art: The art is ok; the characters are well done, especially most of the servants. Overall I have no bones to pick with the animation; it just wasn't that original and the main protagonist had not impressive characteristics to make him stand out. The battle art was very good though; especially their final attacks.
Sound: The sound, like the art was acceptable. The opening and ending themes were very good and the OST was great. There was no real "Epic Battle" music that lived up to some of the great battles, but it was still good.
Characters: This was the big downfall for the series... Most of the characters are very superficial, unoriginal, and predictable. The biggest let down in Saber and several other servants; because the story focuses on the character development of the masters for the most part most of the servants pasts are never explained in any detail... so it makes it very hard to understand their development or motivation. Saber's is insinuated at the very end, but the story rushes so much it makes it impossible to truly understand the depth of her character.
Overall: This in another "Good" anime~
Its worth watching despite its unoriginality~ But don't expect a masterpiece.