Fate/Zero is set in a fictional world based in real life, where "magic" is an important element that the characters in the anime use. In conjunction with magic, the magic users also have the potential to summon familiars, who have been regarded as true warriors/heroes, hence the familiars being historical warriors. Fate/Zero delivers a positive view, based on;
Story
The synopsis of Fate/Zero seems very well done, the characters summon or conjure these familiars in order to beat the 6 other challengers who have also summoned their familiars, all 7 familiars are classified in these classes; Saber - Sword Wielder and one of the three knight classes, Archer - Ranged Projectile and also one of the three knight classes, Lancer - Spear Wielder, also one of the three knight classes, Rider - Cavalry or any other riding characteristics, Caster - Spell/Magic Caster, Assassin - Sneak-like and cunning abilities, and Berserker - Batshit-crazy-strong guy. Taking these classes into account, we get to see how each familiar deals with each other in order to obtain the "Holy Grail", which is supposedly supposed to grant you any wish, and each character and their familiar get to obtain this wish, if they win, by means of; killing all other familiars and/or their masters, of if all other masters are taken out (death or forfeit). The plot certainly gives an interesting aspect to view at, which should not bore you at all, since its a very unique and original idea, this is also before the events of Fate/Stay Night, and if you are having trouble deciding which one to watch, I recommend the release order, which is Fate/Zero, then the events of Fate/Stay Night, and is also even the chronological order. Story is 7/10.
Art
The animation and artwork in Fate/Zero has improved with its new studio producing on it - Studio Ufotable, in the original anime, Fate/Stay Night, the art was not as good as Fate/Zero, but that was because the original anime did production during the early 2000s, which does not quite match up with today's current anime artwork, but still, the animation and art in Fate /Zero has been done very well, it looks very modern, which can be watched easily with fascination entertainingly, even the anime surpasses most other anime in today's time with the animation and art. Art is 8/10.
Sound
The music presented in Fate/Zero is also good, the openings and endings of the anime sounds very nice, it combines various instruments in conjunction with harmonious melodies which is so cool! The soundtrack is mediocre, but the sound effects in the anime is amazing, it sound so nice when destruction is caused and the weapons clashing with each other. Sound is 7/10.
Character
Most characters in Fate/Zero have at least medium detail regarding the character plot and their development, which is really good, as most anime do not concern the character's history and their development in full detail, but Fate/Zero says otherwise. The characters are very interesting, and the history of the familiars do relate to actual historical figures, which is pretty amazing. The research done on the characters is magnificent, well done Type-Moon and Kadokawa Shoten, in at least providing character details. Character is 8/10.
Enjoyment
Of course, the anime delivers a positive view on whoever watches this anime, as every episode just keeps you on edge; the action, the thrills, the tsundere moments with Rin Tohsaka, some comedy, and possible romance keeps the anime balanced. I can guarantee that you will be entertained during and after watching the anime. Enjoyment is 9/10.
Overall
Ultimately, Fate/Zero has many positive aspects about it; the story, art, sound, character, and enjoyment, will keep you watching this anime, and give you wonderful experiences and moments that you will be able to feel when you watch Fate/Zero. Overall score is 8/10.