I thought that Fate/Stay Night was actually a really good show. For the most part, the animation was excellent, and the music played out pretty nicely as well. Despite these things though, it did tend to feel a little slow at times, although that could just be me. The plot was fine: intriguing, exciting, and it kept me at the computer for several hours. The action in the show is pretty great, too, especially if you're a person who loves to see a special, flashy attack from various characters in a series. :) There are plenty of those to be had here, making each fight have a very climactic feel near the end of the battles, which, to me, is a good thing.
Furthermore, all the characters have very in-depth personalities, which make them all that much more interesting and curious to observe.
This show is definitely worth checking out.