Fate/Stay Night is an anime series based on a Japanese Visual Novel made by TYPE-MOON that was released in Japan only on PC & PS2. As a disclaimer to this review, I have not read the original Visual Novel so I can't make any comparisons of how well the original work was adapted into an anime series. The Fate/Stay Night Visual Novel, however, is reportedly one of the best selling visual novels of all time in Japan.
I did read some summaries of the visual novel, however, so I do know that the original visual novel had 3 storyline arcs: the "Fate" arc, the "Unlimited Blade Works" arc, and the "Heaven's Feel" arc. This anime is primarily based on the "Fate" arc, though it also casually blends in a few elements of the other arcs.
In Fate/Stay Night, the main character, Shiro Emiya, is the adopted son of a Magi, who has passed away by the start of the series. Shiro was found in the midst of a huge fire 10 years ago and was saved by his father. Despite his adopted father being a Magi, Shiro was not taught any magic. However, he has practiced a little of his own; he has the ability to re-enforce objects. Before long, Shiro is drawn into the "Holy Grail War", an event that occurs every ten years.
In the "Holy Grail War", 7 masters are chosen that descent from the magi. Each chosen master summons a servant of one of seven classes: Saber, Archer, Lancer, Rider, Caster, Assassin, and Berserker. The masters and servants must face off in a series of battles that have to be fought in secret and can only be fought at night. The battles continue until only one is left standing; at this point, the holy grail will appear and grant the wish of the master and servant.
As Shiro is drawn into the war against his will after he inadvertently summons Saber, he decides to fight to prevent anyone from dying, desiring to become a hero of justice. As the war continues, Shiro comes to find how the war relates to his past, as he was found ten years ago… in the flames of the previous war.
Animation is easily the greatest strength of Fate/Stay Night. The animation is downright beautiful and you can tell that AAA quality effort was put into every last little detail of the entire series. The creators even bothered to paint a unique pattern on background of the opening Fate/Stay Night logo for each individual episode. This anime is quite possibly the most beautiful anime series I've ever seen; I wish the series was also available on Blu-Ray so that it could truly display its beauty.
The music of Fate/Stay Night is excellently done; it adds a mysterious feel to the anime that helps set the mood for the events that occur. The first opening theme "disillusion" and its animation sets a great mysterious feeling for the beginning of the series in my mind. The second theme, "Kirameku Namida wa Hoshi ni" helps set a more serious mood for the second half of the series after the major turning point occurs.
Characters are a great strength of Fate/Stay Night. One of the funnest parts of watching Fate/Stay Night was trying to figure out the true identities of the servants; some are given to you, while others are left for you to figure out on your own. Archer in particular is a very fun and epic one to figure out.
Besides the servant's identities, I liked most of the main characters. I disliked Shiro at first but began to like him in the second half of the anime due to the way his character changed as the series moved on. Rin was my favorite character out of the master's, and I loved how innocently evil Illya was too.
SUB VS. DUB?
You could go either way with this one, but I actually really like the dub for Fate/Stay Night. While both tracks are good, the dub was very high quality for a English dub and I feel that all of the characters were sufficiently and accurately voiced. In particular, for my two favorite characters, Rin and Archer, I actually like the English voice actors better than the Japanese actors. Liam O'Brien does an excellent job as Archer and he is a perfect fit for him. However, for those who prefer subs, you can definitely go either way: as I said, both tracks are good so pick whichever one you prefer.
Fate/stay Night is an excellent anime all around; especially if you fully understand the implications of the story and how all the servants relate to their masters. Fate/stay Night kept me watching episode after episode to until the very end; I couldn't stop. I highly recommend that everyone at least give the series a shot.