The "Fate" series, steming from Type-Moon's visual novel "Fate / Stay Night," can be a little intimidating. As of this writing (2018), there are several adaptations, consisting of multiple retellings of the original source, plus prequels, alternate universes, and complete spin-offs that range from magical-girls to comedy to slice-of-life comfort. If you don't know where to start, and what to experience the dark-fantasy action drama that the series is mostly known for, I highly recommend starting with "Fate / Zero." It's a prequel to the original story, but despite what other fans may claim, I think you can get full enjoyment from the series without watching any of the original material. In some ways, you are better off watching "Fate / Zero" and not watching anything else. If I seem praiseworthy of it, its with good reason: "Fate / Zero" is the cloest I have seen to a flawless fantasy anime.Much of its success comes from how "Fate / Zero" doesn't talk down to its viewer. It's one of the very few anime that doesn't have the slightest bit of sexual fanservice, despite other entries in the franchise having ample amounts of it. The double-length first episode does a great job with the setup, but takes its time with smart pacing (a handful of characters do not get introduced until episode 2). Basically, every generation or so, a "Holy Grail War" is held among the secret society of mages around the world. The War is fought between mages and their servants, each mage being allowed to summon one legendary servant from history to represent them (examples in this show include "Alexander the Great," "Gilgamesh," and others). They fight to win the Holy Grail, a chalice that only manifests itself during the war, and is said to be capable of granting any one wish. The seven competitors each have their time in the show, and each are distinct from one another. They each have their own reasons to win, and their own methods to fight. The lead protagonist is arguably Kiritsugu Emiya, paired with Saber, aka. a cleverly female version of who we called King Arthur, but Kiritsugu is a mercenary hired by a struggling mage family to win in their place, and typically resorts to underhanded methods, from guns and bombs, to blackmail and espionage, making it uncertain that he would really win or that we want him to. Other competitors have their own reasons to fight, from understanding the magical root of all existance, to proving their worth to their superiors, to simply having fun killing everything. Pacing is deliberately slow, and action battles aren't as frequent as you might think: most of the show is of characters carefully planning and occasionalyl discussing their convictions. This war only happens every few decades, after all, and characters are likely to not live to the end, so they cannot afford to make mistakes. This all comes together in what feels like a smart and engrossing fantasy with the best pacing I can remember, with a powerful climax and satisfying ending.A quick side-note on some side-effects of the story: the anime takes creative liberties with depicting its legendary heroes, and it is the first show I've watched to make me want to research the individual people that inspired these characters. It's a great example of the right way to encourage education, so recommend this to your children to help them study! On the other hand, the original story was written by Gen Urobuchi, later dubbed "the Butcher," and while he is one of anime's strongest writers of the 21st century, he also tends to get really dark and vioent. Many characters, both important and not, die on screen, often in grisly and bloody ways. Most of them innocent children. Some of the imagery towards what children go through in this show come close to satisfying unhealthy fetishes, and is more likely to disturb and turn off some viewers (and from what I hear, the manga based on the original novel is even more gruesome). It doesn't effect my personal thoughts on the story as a whole (even the odd side-steps into subplots that feel out of place in the overall context didn't phase me too hard), but don't let young audiences come near this show, and be warned before watching. 
Visually, both in style and execution, "Fate / Zero" is a triumph. Studio Ufotable had cut their teeth in challenging their teams on the "Gardent of Sinners" film series, creating a new standard in detail, digital effects and coloring of 2D animation. That is perfected here, and the studio arguably got too comfortable in subsequent shows, so this is still among the best you can find in anime. The character designs are beautfiul, begging to be placed on posters and wallpapers, and the backgrounds in detail and lighting set a new benchmark. Animation is solid throughout, and reaches highs during the action scenes, the speed and flashiness of which has been improved on since "Fate / Zero" 's release, but this doesn't reduce the effect at all here. Certain imagery, like the moonlight reflecting over the ocean, or blood overflowing from a challice, or an empty battlefield of corpses, all help make this an excellent example of style with substance.The music is by Yuki Kajiura, around the time when she was getting very popular. This isn't her best work, but it is still very good, with memorable orchestral and choir scores during both batttle-heavy and quiet moments. The opening and ending themes remain among my favorite pop songs, and that helps push the score higher. The English dub acting is respectively good, but the Japanese dub is slightly better: regardless, there are many opportunities to showcase a wide array of emotions for each character, and you should feel satisfied either way. If I had watched "Fate / Stay Night" (any adaptation) after this (hint: I have), it might have reduced my opinion slightly, as I would know the story doesn't get much better than it does here. Even without that context, "Fate / Zero" stands perfectly on its own, any hints to future arcs are satisfying to imaging without explicitly seeing that side of the story. If you like "Game of Thrones" or "House of Cards," and don't commonly watch anime, this could be the getway anime for you.