This review covers both seasons because they're both parts of the same story and reviewing them individually is stupid.
Fate/zero is yet another badly written anime by the shitty writer gen urobuchi and this review explains why.
I'll talk about the good aspects of fate/zero and then the majority of the review will be the bad aspects (because there are too many) the mediocre aspects are anything that i don't end up mentioning
The Good:-
1- Great Visuals that make the scenes and the backgrounds in the anime look great, but the anime doesn't have alot of animation in it.
2- high quality instruments and sound effects, but the soundtrack itself is not that amazing in fact most of it is forgettable.
The Bad:-
1- the grail war in this anime never had any clear rules at all.
No rules were mentioned at the beginning, instead the writer inserted any rules he wanted as the anime went on, even the basis of how magic works were unclear and he wrote them as he went on and made magic adjust to any given situation, which shows how badly written this anime is. An example of this is Kirei blocking Kiritsugu's origin bullets using command spells which doesn't make any sense.
2- Character problems:-
The masters
Kiritsugu Emiya: used to live happily in an island and after like five minutes it turns into hell with zombie infection, so cheesy and unrealistic, then he kills his father who raised him because he was only partly and indirectly responsible for the zombie infection and it was only by accident, it seems like the writer doesn't even know how people normally behave.
Kotomine Kirei: starts as a normal guy who works with tokiomi but after archer tells him that he seems intrested in kariya's tragedy he gets rewritten into a one-dimensional villan by instantly betraying tokiomi and seeking the grail that will help him understand himself, which is dumb since an individual normally understands himself more than anyone else, like i said earlier, the writer doesn't even know how people normally behave.
Matou Kariya: who suffers to join the war so he can save sakura, but fails to do so and suffers even more, the only reason he exists is because the writer is obsessed with tragedy, kariya's story has no point, no meaning, it's a complete waste of time.
El-Melloi Archibald Kayneth: an uninteresting and boring asshole.
The servants
Saber (king arthur): ripping a character straight from historical books into your anime without bothering to include her background which is necessary to understand her unremarkable struggles in the anime, it seems like the writer has achieved new levels of bad storytelling.
Berserker (Sir Lancelot):same problem as saber.
Caster & his master(Gilles de Rais & Ryuunosuke): both of them don't even care about the grail, they simply spend their time killing kids and talking about how they enjoy killing kids, they're too delusional to even see the possible consequences of their actions like being the first ones killed in the grail war, which actually happens, but why are these characters in the anime anyways? oh yeah because they need SHOCKING scenes in it to attract viewers who only care about SHOCK FACTOR.
Archer (gilgamesh): an egoistical asshole with hax god powers (which he used to kill rider) he doesn't have to worry about anything thanks to his hax powers, which lets him remain as an egoistical asshole with zero character development till the end, he could have also won the war straight from the beginning but he doesn't care about the war, why is he in this anime again? You can remove him from the anime without any changes.
3- Shoehorned philosophy & themes.
The writer adds unnecessary philosophy & themes to the anime with a very bad handling of them.
- the anime wasted time by having rider and archer talk about how they think saber was not a good king, her life as a king was not shown in the anime and wasn't even part of the anime story in the first place, so why are they discussing it? It makes no sense, even if it made sense it still wouldn't matter because it doesn't affect the anime story, and why are they referring to her as king? she's a woman which makes her a queen.
- after lancer's death saber complains about Kiritsugu's evil actions in the grail war, out of stupidity she forgets that he will use the grail to end war.
then Kiritsugu claims that honor and valor are the cause of war and bloodshed, yet any one with half a brain can tell how stupid that claim is, the people who got honor from war did it by not commiting war crimes against anyone during war and did what it takes to reduce the losses and hatered of war after it was over, the war itself was not caused or started by them ,The people who cause or start a war usually do it for other reasons without bothering to think of the consequences, they can't do it because of honor since it has no way of starting a war by itself, there is always another reason behind it, if the writer knows of significant bloodshed caused by honor he should mention and explain it, otherwise it comes of as pretentious and stupid, another fact is almost everybody nowadays knows that war itself is bad and nobody think's that war itself is honorable or anything, yet Kiritsugu acts like he figured out something special, it's as if the writer lives in his own small world and keeps including topics in the anime that he himself doesn't even understand.
4- The ending:-
Which literally ruined the entire story with it's bullshit.
At the beginning everyone talks about how the grail will grant any wish and nobody doubts it at all and they do all it takes to win the grail but then right at the end it's revealed that the grail won't actually grant any wish, more specificly it won't be able to grant the wish of the winner (Kiritsugu) and then it explodes and kills everything around him, this happened because the grail was cursed before fate/zero and that's only known in other parts of the fate franchise which you have to through to understand this because it wasn't mentioned or probably foreshadowed at any part of the fate/zero anime, if fate/zero doesn't even make sense on it's own and has many writing problems then how can it be any better than the rest of the fate (porn game) franchise? even if the grail got cursed, then why didn't any of the characters know about the curse or doubt the grail? it makes no sense either.
and this ending basically makes the entire anime feel like a pointless waste of time.
Kiritsugu, after bad writing destroyed everything he was doing without any explained reason is still happy because he saved and adopted shirou at the end which ties this with fate/stay night, yay i don't care.